Magnetism And Matter — Physics STD 12 Science — Question

Assertion  :  The drift velocity of electrons in a metallic wire will decrease, if the temperature of the wire is increased.

Reason      : On increasing temperature, conductivity of metallic wire decreases.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

Peak value of applied alternating voltage in a LR cir- cuit is 5 V. If magnitude of maximum voltage across the ends of resistor is 3 V. then maximum value of voltage across the inductor is

For a given surface the Gauss's law is stated as  From this we can conclude that         

(a) E is necessarily zero on the surface

(b) E is perpendicular to the surface at every point

(c) The total flux through the surface is zero

(d) The flux is only going out of the surface

The turn ratio of a transformers is given as 2 : 3. If the current through the primary coil is 3 A, thus calculate the current through load resistance

(a) 1 A

(b) 4.5 A

(c) 2 A

(d) 1. 5 A

In one second, a current of 10 A changes through a coil. The induced emf is 10V, then, self-inductance of the coil is 

The cathode rays have particle nature because of the fact that

(a) They can propagate in vacuum

(b) They are deflected by electric and magnetic fields

(c) They produced fluorescence

(d) They cast shadows

A thin lens made of glass of refractive index 1.5 has a front surface + 11 D power and back surface – 6 D. If this lens is submerged in a liquid of refractive index 1.6, the resulting power of the lens is

(a) – 0.5 D

(b) + 0.5 D

(c) – 0.625 D

(d) + 0.625 D

A non.monochromatic light is used in an experiment on photoelectric effect. The stopping potential:

 If a variable frequency ac source is connected to a capacitor then with decrease in frequency the displacement current will:

An electric filament bulb can be worked from: