# CBSE Sample Paper Class 12 Physics

PHYSICS

Class XII

Electrostatics , Current-Electricity & Magnetism

Q.1> Define Coulomb. Calculate the charge carried by 12.5×1018 electrons.

Q.2> Define resistivity of a material. Does it depend on temp?

Q.3> How many protons will have the total charge of 1C

Q.4> Find the current drawn when a battery of emf E and internal resistance r is connected across an external resistance R

Q.5> State Faraday’s laws of electrolysis. Define electrochemical equivalent

Q.6> An electron travels in a circular path of radius 20cm in a magnetic field of 2mT. Calculate the speed of the electron. What is the potential difference through which the electron must be accelerated to acquire this speed?

Q.7> Explain how you will convert a galvanometer into a voltmeter of a given range

Q.8> State Gauss’s law in electrostatics. Apply this to show that for a spherical shell, the electric field inside the shell vanishes whereas outside it, the field is as if all the charge had been concentrated at the center.

Q.9>State the 2 Kirchoff law

Q.10> Show that in a uniform electric field, a dipole experiences only a torque but no net force. Derive expression for the torque.

Q.11> An electron moving with a velocity of 108m/s enters a magnetic field of 50G in a direction perpendicular to it. Calculate (a) Radius of the path and (b) Frequency of revolution

Q.12> Define Capacitance. Show that the energy density in a parallel plate capacitor is 1/2?oE2

Q.13> Why 2 electric field lines do not intersect?

Q.14> Define magnetic moment of a dipole and give its SI unit.

Q.15> How does the velocity of a charged particle affect its (a) Mass (b) Charge

Q.16> Explain Seebeck effect. What is the use of the Seebeck series?

Q.17> State one main difference b/w primary and secondary cells.

Q.18> An oil drop of weight 3.2×10-14Kg is balanced in an electric field of 5×105V/m, find the charge on the oil drop.

Q.19> The sequence of bands marked on a carbon resistor are Yellow, Red,Orangeand silver. Find the resistance and the tolerance

Q.20> The coil of a galvanometer has a resistance of 100ohm. It shows full scale deflection for a current of 0.5mA. How will you convert it into a voltmeter to read a potential difference of 5Volts.

Q.21> Find the magnetic moment associated with a coil of 10 turns, area 10-4m2 and carrying a current of 2A

Q.22> A dry cell of EMF 1.5 volts and internal resistance 0.1ohm if connected to a resistor R. If the current drawn from the cell if 2A, find the voltage drop across R and power dissipated in it.

Q.23> The work done in moving a charge of 3C from A to B is 6J. Find the potential difference b/w A and B

Q.24> Derive the expression for the torque on a rectangular coil of area A carrying current I placed in a magnetic field B. The angle b/w direction of B and the area vector of the coil is ?.

Q.25> What is a dielectric? A dielectric slab of thickness t is placed b/w the plates of a parallel plate capacitor having plate separation d and plate area A. Derive the capacitance.

Q.26> Find the electric field b/w 2 metal plates 5mm apart, connected by a 12V battery.

Q.27> Write an expression connecting the thermo-electric emf with temp difference.

Q.28> Give the colour sequence for a 47Kohm resistor.

Q.29> Write two special characteristics of the wire of an electric heater.

Q.30> A metallic wire of length 1m is stretched to double its length. Calculate the ratio of initial to final resistance.

Q.31> Explain

(a)   An ammeter is a low resistance device and it is always connected in series

(b)   A good voltmeter should have high resistance and it is always connected in parallel

Q.32> Name 2 materials which are used for making standard resistance coils. Why are these materials preferred over others?

Q.33> When a potentiometer is connected b/w A and B the

balance length is 300cm. On connecting the potentiometer          A                         B                         C

across A and C, the balance length is 100cm. Find E1/E2

Q.34> Find the magnetic field at the center of the circular loop shown here          10A

Q.35> Define angle of dip. What is the angle of dip at (a) Poles (b) Equator

Q.36> A charge of 12C is given to a hollow sphere of radius 0.1m. Find the potential at the surface and at the centre of the sphere.

Q.37> A battery of emf 3 volts and internal resistance r is connected in series with a resistor of 55ohm through an ammeter of 1?. The ammeter reads 50mA. Draw the circuit diagram and calculate the value of r.

Q.38> With the help of a suitable diagram, explain the construction and working of a dry cell.

Q.39> A set of n identical resistors each of resistance R, when connected in series give a net of X ohm and when connected in parallel give a net of Y ohm. Show that XY=R2

Q.40> A long straight wire carries a current of 3A. Calculate the magnitude of magnetic field at a distance of 10cm from the wire. Draw a diagram to show that a current carrying wire has no poles.

Q.41> A beam of electrons passes undeflected through a region of mutually perpendicular E and B. If the electric field is cut-off, the electron beam moves in a circular path of radius R. Derive an expression for the e/m ration of the electrons in terms of E, B and R.

Q.42> Give 2 factors on which thermo-electric emf depends

Q.43> Two point electric charges A and B of unknown magnitude and sign are placed d distance apart. The electric field is zero at a point, not b/w the charges but on the line joining them and closer to A. Write 2 essential conditions for this to happen

Q.44> Define sensitivity of a potentiometer. How can it be increased.

Q.45> Mention one main difference b/w primary and secondary cell.

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