# 2nd Year Physics Important Questions

## 2nd Year Physics Important Questions On Newsongoogle By Bilal Articles

Embark on an emotional odyssey with Bilal Articles on Newsongoogle! Dive into the brilliance of Class 12 Physics—unlock the secrets of every chapter with all-encompassing notes, relive the intensity of past papers, and experience the thrill of uncertainty with Physics guess papers. Brace yourself for a journey of discovery with essential long and short questions for 2nd Year Physics. Let the emotions flow, and let success become your story.

**2nd Year Physics Important Questions 1st Lesson Waves**

- Write the formula for speed of sound in solids and gases.
- What does a wave represent ?
- Distinguish between transverse and longitudinal waves.
- What are the parameters used to describe a progressive harmonic wave ?
- What is the principle of superposition of waves ? .
- Under what conditions will a wave be reflected ?
- What is the phase difference between the incident and reflected waves when the wave is reflected by a rigid boundary ?
- What is a stationary or standing wave ?
- What do you understand by the terms node’ and ‘antinode’ ?
- What is the distance between a node and an antinode in a stationary wave ?
- What do you understand by ‘natural frequency’ or ‘normal mode of vibration’ ?
- What are harmonics ?
- A string is stretched between two rigid supports. What frequencies of vibration are possible in such a string ?
- If the air column in a long tube, closed at one end, is set in vibration, what harmonics are possible in the vibrating air column ?
- If the air column in a tube, open at both ends, is set in vibration; what harmonics are possible ?

**Long Questions**

- What are transverse waves ? Give illustrative examples of such waves.
- What are longitudinal waves ? Give illustrative example of such waves.
- What are ‘beats’ ? When do they occur ? Explain their use, if any.
- What is ‘Doppler effect’ ? Give illustrative examples.
- Explain the formation of stationary waves in stretched strings and hence deduce the laws of transverse wave in stretched strings.
- Explain the formation of stationary waves in an air column enclosed in open pipe. Derive the equations for the frequencies of the harmonics produced.
- What is Doppler effect ? Obtain an expression for the apparent frequency of sound heard when the source is in motion with respect to an observer at rest.

**2nd Year Physics Important Questions Chapter 2 Ray Optics and Optical Instruments**

- What is optical density and how is it different from mass density ?
- What are the laws of reflection through curved mirrors ?
- Define ‘power’ of a convex lens. What is its unit ?
- A concave mirror of focal length 10 cm is placed at a distance 35 cm from a wall. How far from the wall should an object be placed so that its real image is formed on the wall ?
- A concave mirror produces an image of a long vertical pin, placed 40cm from the mirror, at the position of the object. Find the focal length of the mirror.
- A small angled prism of 4° deviates a ray through 2.48°. Find the refractive index of the prism.
- What is ‘dispersion’? Which colour gets relatively more dispersed ?
- The focal length of a concave lens is 30 cm. Where should an object be placed so that its image is 1/10 of its size ?
- What is myopia ? How can it be corrected ?
- What is hypermetropia ? How can it be corrected ?
- Draw neat labelled ray diagram of simple microscope.
- Define focal length of a concave mirror. Prove that the radius of curvature of a concave mirror is double its focal length.
- Define critical angle. Explain total internal reflection using a neat diagram.
- Explain the formation of a mirage.
- Explain the formation of a rainbow.
- Why does the setting sun appear red ?
- With a neat labelled diagram explain the formation of image in a simple microscope.
- What is the position of the object for a simple microscope ? What is the maximum magnifi-cation of a simple microscope for a realistic focal length ?

**Long Questions**

- Draw a neat labelled diagram of a compound microscope and explain its working. Derive an expression for its magnification.
- Define Snell’s Law. Using a neat labelled diagram derive an expression for the refractive index of the material of an equilateral prism.
- A ray of light, after passing through a medium, meets the surface separating the medium from air at an angle of 45° and is just not refracted. What is the refractive index of the medium ?
- Suppose that the lower half of the concave mirror’s reflecting surface in figure is covered with an opaque (non- reflective) material. What effect will this have on the image of an object p’ iced in front of the mirror ?
- A mobile phone lies along the principal axis of a concave mirror, as shown in Fig. Show by suitable diagram, the formation of its image. Explain why the magnification is not uniform. Will the distortion of image depend on the location of the phone with respect to the mirror ?

**2nd Year Physics Important Questions 3rd Lesson Wave Optics**

- Explain Doppler effect in light. Distinguish between red shift and blue shift.
- Derive the expression for the intensity at a point where interference of light occurs. Arrive at the conditions for maximum and zero intensity.
- Does the principle of conservation of energy hold for interference and diffraction phenomena? Explain briefly.
- Explain polarisation of light by reflection and arrive at Brewster’s law from it.
- Discuss the intensity of transmitted light when a polaroid sheet is rotated between two crossed polaroids.

**Long Questions**

- Distinguish between Coherent and Incoherent addition of waves. Develop the theory of constructive interferences.
- Describe Young’s experiment for observing interference and hence arrive at the expression for ‘fringe width’.
- What speed should a galaxy move with respect to us so that the sodium line at 589.0 nm is observed at 589.6 nm ? .
- Unpolarised light is incident on a plane glass surface. What should be the angle of the incidence so that the reflected and refracted rays are perpendicular to each other ?
- What is the Brewster angle for air to glass transition ?
- In Young’s double-slit experiment using monochromatic light of wavelength λ, the intensity of light at a point on the screen where path difference is λ, is K units. What is the intensity of light at a point where path difference is λ/3 ?

**2nd Year Physics Important Questions 4th Lesson Electric Charges and Fields**

- What is meant by the statement ‘charge is quantized’?
- Repulsion is the sure test of charging than attraction. Why ?
- How many electrons constitute 1 C of charge ?
- What happens to the weight of a body when it is charged positively ?
- What happens to the force between two charges if the distance between them is
- Consider two charges + q and -q placed at B and C of an equilateral triangle ABC. For this system, the total charge is zero. But the electric field (intensity) at A which is equidistant from B and C is not zero. Why ?
- Electrostatic field lines of force do not form closed loops. If they form closed loops then the work done in moving a charge along a closed path will not be zero. From the above two statements can you guess the nature of electrostatic force ?
- State Gauss’s law in electrostatics. [IPE 2015 (TS)]
- When is the electric flux negative and when is it positive ?
- Write the expression for electric intensity due to an infinite long charged wire at a distance radial distance r from the wire.
- Write the expression for electric intensity due to an infinite plane sheet of charge.
- Write the expression for electric intensity due to a charged conducting spherical shell at points outside and inside the shell.
- A proton and an α-particle are released in a uniform electric field. Find the ratio of (a) forces experienced by them (b) accelerations gained by each.
- A hollow sphere of radius ‘r’ has a unifrom charge density ‘σ’. It is kept in a cube of edge 3r such that the center of the cube coincides with the center of the shell. Calculate the electric flux that comes out of a face of the cube.
- Consider a uniform electric field AP Inter 2nd Year Physics Important Questions Chapter 4 Electric Charges and Fields 1. What is the flux of this field through a square of 10 cm on a side whose plane is parallel to the YZ plane ?
- State and explain Coulomb’s inverse square law in electricity.
- Derive an expression for the intensity of the electric field at a point on the axial line of an electric dipole.
- State Gauss’s law in electrostatics and explain its importance.

**Long Questions**

- State Gauss’s law in electrostatics. Applying Gauss’s law derive the expression for electric intensity due to an infinite plane sheet of charge.
- How can you charge a metal sphere positively without touching it ?
- If 109 electrons move out of a body to another body every second, how much time is required to get a total charge of 1 C on the other body? .
- How much positive and negative charge is there in a cup of.water ?
- Consider the charges q, q and -q placed at the vertices of an equilateral triangle, as shown in Fig. What is the force on each charge ?
- Two charges 10 μC are placed 5.0 mm apart. Determine the electric field at (a) a point P on the axis of the dipole 15 cm away from its centre O on the side of the positive charge, as shown in Fig. (a) and (b) a point Q, 15 cm away from O on a line passing through O and normal to the axis of the dipole, as shown in Fig.

### 2nd Year Physics Important Questions Chapter 5 Electrostatic Potential and Capacitance

- Derive an expression for the electric potential due to a point charge.
- Derive an expression for the electrostatic potential energy of a system of two point charges and find its relation with electric potential of a charge.
- Derive an expression for the potential energy of an electric dipole placed in a uniform electric field.
- Derive an expression for the capacitance of a parallel plate capacitor.
- Explain the behaviour of dielectrics in an external field.
- Define electric potential. Derive an expression for the electric potential due to an electric dipole and hence the electric potential at a point (a) the axial line of electric dipole (b) on the equatorial line of electric dipole.
- What is series combination of capacitors. Derive the formula for equivalent capacitance in series combination.
- What is parallel combination of capacitors. Derive the formula for equivalent capacitance in parallel combination.
- Derive an expression for the energy stored in a capacitor.
- What is the energy stored when the space between the plates is filled with dielectric.
- A slab of material of dielectric constant K has the same area as the plates of a parallel plate capacitor but has a thickness (3/4)d, where d is the separation of the plates. How is the capacitance changed when die slab is inserted between the plates ?

**Long Questions**

- Four charges are arranged at the comets of a square ABCD of side d. as shown in fig. 5.15.(a) Find the work required to put together this arrangement, (b) A charge q0 is brought to the centre of the square, the four charges being held fixed at its comers. How much extra work is needed to do this ?
- How much work is required to separate the two charges infinitely away from each other ?
- A molecule of a substance has a perma-nent electric dipole moment of magnitude 10-29C m. A mole of this substance is polarised (at low temperature) by applying a strong electrostatic field of magnitude 106 V m-1. The direction of the field is suddenly changed by an angle of 60°. Estimate the heat released by the substance in aligning its dipoles along the new direction of the field. For simplicity, assume 100% polarisation of the sample.
- A comb run through one’s dry hair attracts small bits of paper. Why ? What happens if the hair is wet or if it is a rainy day ? (Remember, a paper does not conduct electricity.)
- Ordinary rubber is an insulator. But special rubber types of aircraft are made slightly conducting. Why is this necessary ?
- Vehicles carrying inflammable materials usually have metallic ropes touching the ground during motion. Why?
- To enable them to conduct charge (produced by friction) to the ground; as too much of static electricity accumulated may result in spark and result in fire.

### 2nd Year Physics Important Questions Chapter 6 Current Electricity

- Derive an expression for the effective resistance when three resistors are connected in (i) series (ii) parallel.
- On what factors does the resistance of a conductor depend ? Define electric resistance and write its S.I unit. How does the resistance of a conductor vary if (a) Conductor is stretched to 4 times of its length (b) Temperature of conductor is increased ?

**Long Questions**

- State Kirchhoffs law for an electrical network. Using th&se laws deduce the condition for balance in a Wheatstone bridge.
- State the working principle of potentiometer explain with the help of circuit diagram how the emf of two primary cells are compared by using the potentiometer. [A.P. Mar. 16]
- State the working principle of potentiometer. Explain with the help of circuit diagram how the potentiometer is used to determine the internal resistance of the given primary cell. [A.P. & T.S. Mar. 17, 15]
- Under what condition is the heat produced in an electric circuit a)directly proportional b) inversely proportional to the resistance of the circuit ? Compute the ratio of the total quantity of heat produced in the two cases.
- A 10Ω thick wire is stretched so that its length becomes three times. Assuming that there is no change in its density on stretching, calculate the resistance of the stretched wire.
- A wire of resistance 4R is bent in the form of a circle. What is the effective resistance between the ends of the diameter ?
- Three resistors 3Ω, 6Ω and 9Ω are connected to a battery. In which of them will the power of dissipation be maximum if:
- A silver wire has a resistance of 2.1Ω at 27.5°C and a resistance of 2.7Ω at 100°C. Determine the temperature coeff. of resistivity of silver.

**2nd Year Physics Important Questions 7th Lesson Moving Charges and Magnetism**

- What is the importance of Oersted’s experiment ?
- State Ampere’s law and Biot-Savart’s law.
- Write the expression for the magnetic induction at any point on the axis of a circular current-carrying coil. Hence, obtain an expression for the magnetic induction at the centre of the circular coil.
- A circular coil of radius T having N turns carries a current “i”. What is its magnetic moment ?
- What is the force on a conductor of length L carrying a current “i” placed in a magnetic field of induction B ? When does it become maximum ?
- What is the force on a charged particle of charge “q” moving with a velocity “v” in a uniform magnetic field of induction B ? When does it become maximum ?
- Distinguish between ammeter and voltmeter.
- What is the principle of a moving coil galvanometer ?
- What is the smallest value of current that can be measured with a moving coil galvanometer ?
- How do you convert a moving coil galvanometer into an ammeter ?
- How do you convert a moving coil galvanometer into a voltmeter ?
- What is the relation between the permittivity of free space e0, the permeability of free space m0 and the speed of light In vaccum?
- A current carrying circular loop lies on a smooth horizontal plane. Can a uniform magnetic Held be set up in such a manner that the loop turns about the vertical axis ?
- A wire loop of irregular shape carrying current is placed in an external magnetic field. If the wire is flexible, what shape will the loop change to ? Why ?

**long Questions**

- State and explain Biot-Savart’s law.
- State and explain Ampere’s law.
- Find the magnetic induction due to a long current carrying conductor.
- Derive an expression for the magnetic induction of a point on the axis of a current carrying circular coil using Biot-Savart’s law.
- Explain how crossed E and B fields serve as a velocity selector.
- What are the basic components of a cyclotron ? Mention its uses ?
- Derive an expression for the magnetic dipole moment of a revolving electron.
- Deduce an expression for the force on a current carrying conductor placed in a magnetic field. Derive an expression for the force per unit length between two parallel current-carrying conductors.
- Obtain an expression for the torque on a current carrying loop placed in a uniform ‘ magnetic field. Describe the construction and working of a moving coil galvanometer.
- How can a galvanometer be converted to an ammeter ? Why is the parallel resistance smaller that the galvanometer resistance ? A moving coil galvanometer can measure a current of 10-6 A. What is the resistance of the shunt required if it is to measure 1A ?
- How can a galvanometer be converted to a voltmeter ? Why is the series resistance greater that the galvanometer resistance ? A moving coil galvanometer of resistance 5Ω can measure a current of 15mA. What is the series resistance required if it is to measure 1.5V ?

### 2nd Year Physics Important Questions Chapter 8 Magnetism and Matter

- A magnetic dipole placed in a magnetic field experiences a net force. What can you say about the nature of the magnetic field ?
- Do you find two magnetic field lines intersecting ? Why ?
- What happens to the compass needles at the Earth’s poles ?
- What do you understand by the ‘magnetisation’ of a sample ? Give its SI unit.
- What is the magnetic moment associated with a solenoid ?
- What are the units of magnetic moment, magnetic induction and magnetic field ?
- Magnetic lines form continuous closed loops. Why ?
- Define magnetic declination.
- Define magnetic inclination or angle of dip.
- Classify the following materials with regard to magnetism: Manganese, Cobalt, Nickel, Bismuth, Oxygen, Copper.
- The force between two magnet poles separated by a distance ‘d’ in air is ‘F’. At what distance between them does the force become doubled ?
- If B is the magnetic field produced at the centre of a circular coil of one turn of length L carrying current I then what is the magnetic field at the centre of the same coil which is made into 10 turns ?
- If the number of turns of a solenoid is doubled, keeping the other factors constant, how does the magnetic field at the axis of the solenoid change ?
- A closely wound solenoid of 800 turns and area of cross section 2.5 × 10-4 m2 carries a current of 3.0A. Explain the sense in which the solenoid acts like a bar magnet. What is its associated magnetic moment ?
- Compare the properties of para, dia and ferromagnetic substances.
- Explain the elements of the Earth’s magnetic field and draw a sketch showing the relationship between the vertical component, horizontal component and angle of dip.
- Define magnetic susceptibility of a material. Name two elements one having positive susceptibility and other having negative susceptibility.
- Derive an expression for magnetic field induction on the equatorial line of a barmagnet. [Board Model Paper]
- What do you understand by “hysteresis” ? How does this propertry influence the choice of materials used in different appliances where electromagnets are used ?
- Prove that a bar magnet and a solenoid produce similar fields.
- A small magnetic needle is set into oscillations in a magnetic field B obtain an expression for the time period of oscillation.
- A bar magnet, held horizontally, is set into angular oscillations in the Earth’s magnetic field. It has time periods T1 and T2 at two places, where the angles of dip are θ1 and θ2 respectively. Deduce an expression for the ratio of the resultant magnetic fields at the two places.

**Long Questions**

- A coil of 20 turns has an area of 800 mm2 and carries a current of 0.5A. If it is placed in a magnetic field of intensity 0.3T with its plane parallel to the field, what is the torque that it experiences ? ,
- In the Bohr atom model the electrons move around the nucleus in circular orbits. Obtain an expression the magnetic moment (p) of the electron in a Hydrogen atom in terms of its angular momentum L.
- A bar magnet of length 0.1m and with a magnetic moment of 5Am2 is placed in a uniform a magnetic field of intensity 0.4T, with its axis making an angle of 60° with the field. What is the torque on the magnet ?
- A solenoid of length 22.5 cm has a total of 900 turns and carries a current of 0.8 A. What is the magnetising field H near the centre and far away from the ends of the solenoid ?
- The horizontal component of the earth’s magnetic field at a certain place is 2.6 × 10-5T and the angle of dip is 60°. What is the magnetic field of the earth at this location ?
- In the magnetic meridian of a certain place, the horizontal component of the earth’s magnetic field is 0.26 G and the dip angle is 60°. What is the magnetic field of the earth at this location ?
- What is the magnitude of the equatorial and axial fields due to a bar magnet of length 8.0 cm at a distance of 50 cm from its mid-point ? The magnetic moment of the bar magnet is 0.40 A m2.
- The earth’s magnetic field at the equator is approximately 0.4 G. Estimate the earth’s dipole moment. .

### 2nd Year Physics Important Questions Chapter 9 Electromagnetic Induction

- What did the experiments of Faraday and Henry show ?
- Define magnetic flux.
- State Faraday’s law of electromagnetic induction.
- State Lenz’s law.
- What happens to the mechanical energy (of motion) when a conductor is moved in a uniform magnetic field ?
- What are Eddy currents ?
- Define ‘inductance’.
- What do you understand by ‘self inductance’ ?
- Obtain an expression for the emf induced across a conductor which is moved in a uniform magnetic field which is perpendicular to the plane of motion.
- Describe the ways in which Eddy currents are used to advantage.
- Obtain an expression for the mutual inductance of two long co-axial solenoids.

**Long Questions**

- A wheel with 10 metallic spokes each 0.5 m long is rotated with a speed of 120 rev/min in a plane normal to the horizontal component of earth’s magnetic field HE at a place. If HE = 0.4 G at the place, what is the induced emf between the axle and the rim of the wheel ? (Note that 1 G = 10-4 T.)
- Number of turns in a coil are 100. When a current of 5A is flowing through the coil, the magnetic flux is 10-6Wb. Find the self induction. [Board Model Paper]
- Current in a circuit falls from 5.0 A to 0.0 A in 0.1 s. If an average emf of 200 V is induced, give an estimate of the self-inductance of the circuit. [Mar. 16 (T.S.) Mar. 14]
- A pair of adjacent coils has a mutual inductance of 1.5 H. If the current in one coil changes from 0 to 20 A in 0.5 s, what is the change of flux linkage with the other coil ? [T.S. Mar. 17]
- A jet plane is travelling towards west at a speed of 1800 km/K What is the voltage difference developed between the ends of the wing having a span of 25 m, if the Earth’s magnetic field at the location has a magnitude of 5 × 10-4 T and the dip angle is 30°.

### 2nd Year Physics Important Questions Chapter 10 Alternating Current

- A transformer converts 200 V ac into 2000 V ac. Calculate the number of turns in the ‘ secondary if the primary has 10 turns.
- What type of transformer is used in a 6V bed lamp ?
- What is the phenomenon involved in the working of a transformer ?
- What is transformer ratio ?
- Write the expression for the reactance of i) an inductor and (ii) a capacitor.
- What is the phase difference between A.C emf and current in the following: Pure resistor, pure inductor and pure capacitor.
- Define power factor. On which factors does power factor depend ?
- What is meant by wattless component of current ?
- When does a LCR series circuit have minimum impedance ?
- What is the phase difference between voltage and current when the power factor in LCR series circuit is unity ?

**Long Questions**

- State the principle on which a transformer works. Describe the working of a transformer with necessary theory.
- A light bulb is rated at 100W for a 220 V supply. Find
- A pure inductor of 25.0 mH is connected to a source of 220 V. Find the inductive reactance and rms current in the circuit if the frequency of the source is 50 Hz.
- The instantaneous current and instantaneous voltage across a series circuit containing resistance and inductance are given by i =
- What is step up transformer ? How it differs from step down transformer ?
- A pure inductor of 25.0 mH is connected to a source of 220 V. Find the inductive reactance and rms current in the circuit if the frequency of the source is 50 Hz.

### 2nd Year Physics Important Questions Chapter 11 Electromagnetic Waves

- Give any one use of infrared rays.
- How are infrared rays produced ? How they can be detected ?
- How are radio waves produced ? How can they detected ?
- If the wave length of E.M radiation is doubled, what happens to the energy of photon ?
- What is the principle of production of electromagnetic waves ?
- What is the ratio of speed of infrared rays and ultraviolet rays in vaccum ?
- What is the relation between the amplitudes of the electric and magnetic fields in free space for an electromagnetic wave ?
- What are the applications of microwaves ?
- Microwaves are used in Radars, why ?
- Give two uses of infrared rays.
- How are microwaves produced ? How can they detected ?
- The charging current for a capacitor is 0.6 A. What is the displacement current across its plates ?
- What physical quantity is the same for X-rays of wavelength 10-10m, red light of wavelength 6800 Å and radiowaves of wavelength 500in ?

**Long Questions**

- State six characteristics of electromagnetic waves.
- What is Greenhouse effect and its contribution towards the surface temperature of earth ?
- A plane electromagnetic wave travels in vaccum along z-direction. What can you say about the directions of its electric and magnetic field vectors ? If the frequency of the wave is 30 MHz. What is its wavelength ?
- A charged particle oscillates about its mean equilibrium position with a frequency of 109 Hz. What is the frequency of the electromagnetic waves produced by the oscillator ?
- A plane electromagnetic wave of frequency 25 MHz travels in free space along the x – direction. At a particular point in space and time, E =

### 2nd Year Physics Important Questions Chapter 12 Dual Nature of Radiation and Matter

- What are “cathode rays” ?
- What important fact did Millikan’s experiment establish?
- What is “work function” ?
- What is “photoelectric effect” ?
- Give examples of “photosensitive substances”. Why are they called so ?
- Write down Einstein’s photoelectric equation.
- Write down de-Broglie’s relation and explain the terms therein.
- State Heisenberg’s Uncertainity Principle. [Mar. 14]
- The photoelectric cut off voltage in a certain experiment is 1.5 V. What is the maximum kinetic energy of photoelectrons emitted ?
- An electron, an α-particle and a proton have the same kinetic energy. Which of these particles has the shortest de Broglie wavelength ?

**Long Questions**

- Calculate the (a) momentum and (b) dE-Brogile wavelength of the electrons accelerated through a potential difference of 56 V.
- Describe an experiment to study the effect of frequency of incident radiation on ‘stopping potential’.
- What is the deBroglie wavelength of a ball of mass 0.12 Kg moving with a speed of 20 ms-1? What can we infer from this result ?
- What is the effect of (i) intensity of light (ii) potential on photoelectric current ?
- How did Einstein’s photoelectric equation explain the effect of intensity and potential on photoelectric current ? How did this equation account for the effect of frequency of ‘ incident light on stopping potential ?

### 2nd Year Physics Important Questions 13th Lesson Atoms

- What is the physical meaning of negative energy of an electron’ ?
- Sharp lines are present in the spectrum of a gas. What does this indicate ?
- Name a physical quantity whose dimensions are the same as those of angular momentum.
- What is the difference between α – particle and helium atom ?
- Among alpha, beta and gamma radiations, which get affected by the electric field ?
- What do you understand by the phrase ground state atom ?
- Why does the mass of the nucleus not have any significance in scattering in Rutherford’s experiment ?
- The Lyman series of hydrogen spectrum lies in the ultraviolet region. Why ?
- Write down a table giving longest and shortest wavelengths of different spectral series.
- Give two drawbacks of Rutherford’s atomic model.
- If the kinetic energy of revolving electron in an orbit is K, what is its potential energy and total energy ?

**Long Questions**

- What is impact parameter and angle of scattering ? How are they related to each other ?
- Explain the distance of closest approach and impact parameter.
- Describe Rutherford atom model. What are the draw backs of this model ?
- Write a short note on Debroglie’s explanation of Bohr’s second postulate of quantization.

### 2nd Year Physics Important Questions Chapter 14 Nuclei

- The half life of 58Co is 72 days. Calculate Its average life.
- Why do all electrons emitted during p-decay not have the same energy?
- Neutrons are the best projectiles to produce nuclear reactions. Why ?
- Neutrons cannot produce ionization. Why ?
- What are delayed neutrons ?
- What are thermal neutrons ? What is their importance ?
- What is the value of neutron multiplication factor in a controlled reaction and in an uncontrolled chain reaction ?
- What is the role of controlling rods in a nuclear reactor ?
- Why are nuclear fusion reactions called thermo nuclear reactions ?
- Define Becquerel and Curie.

**Long Questions**

- Write a short note on the discovery of neutron.
- What are nuclear forces ? Write their properties.
- Define half life period and decay constant for a radioactive substance. Deduce the relation between them.
- What is nuclear fission ? Give an example to illustrate it.
- What is nuclear fusion ? Write the conditions for nuclear fusion to occur.

**2nd Year Physics Important Questions Chapter 15 Semiconductor Electronics: Material, Devices and Simple Circuits**

- What is an n-type semiconductor ? What are the majority and minority charge carriers in it ?
- What are intrinsic and extrinsic semiconductors ?
- What is a p-type semiconductor ? What are the majority and minority charge carriers in it ?
- What is a p-n junction diode ? Define depletion’ layer.
- How is a battery connected to a junction diode in i) forward and ii) reverse bias ?
- What is the maximum percentage of rectification in half wave and full wave rectifiers ?
- What is Zener voltage (Vz) and how will a Zener diode be connected in circuits generally ?
- Write the expressions for the efficiency of a full wave rectifier and a half wave rectifier.
- What happens to the width of the depletion layer in a p-n junction diode when it is
- Draw the circuit symbols for p-n-p and n-p-n transistors.
- Define amplifier and amplification factor.
- In which bias can a Zener diode be used as voltage regulator ?
- Which gates are called universal gates ?
- Write the truth table of NAND gate. How does it differ from AND gate ?

**Long Questions**

- What is a rectifier ? Explain the working of half wave and full Wave rectifiers with diagrams.
- What is a junction diode ? Explain the formation of depletion region at the junction. Explain the variation of depletion region in forward and reverse-biased condition.
- What is a Zener diode ? Explain how it is used as a voltage regulator.
- Explain the working of LED and what are its advantages over conventional incandescent low power lamps.
- Define NAND and NOR gates. Give their truth tables.
- Explain the working of a solar cell and draw its I-V characteristics.

**Related Post:**

- Class 12 Physics All Chapter Notes
- Class 12 Physics Past Paper
- Class 12 Physics Guess paper