On increasing the temperature of a conductor, its resistance increases because the

• relaxation time increases

• electron density decreases

• relaxation time decreases

• relaxation time remains constant

312.

What is the equivalent resistance between A and B in given figure?

           

• 50 Ω

• 25 Ω

• 75 Ω

• 100 Ω

Assertion:  Long distance transmission of a.c. is carried out at extremely high voltages. 

Reason:  Because when the distance is large, voltage has to be large.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Given that the mobility of electrons in Ge is 0.4 m² V^-1  S^-1 and electronic charge is 1.6 × 10^-19 C. The number of donor atom ( per m³ ) semiconductor of conductivity 500 mho/m is

• 8 × 10²¹

• 8 × 10¹⁵

• 5 × 10²¹

• 8 × 10¹⁶

A circuit consisting of five resistors each of resistance R, forming a Wheatstone bridge. What is the equivalent resistance of the circuit?

• 2R

• R

• 2R/3

• R/2

Assertion:  Total current entering a circuit is equal to leaving the circuit by Kirchhoff's law. 

Reason:  It is based on conservation of energy.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

In the given circuit, the voltage across the load is maintained at 12 V. The current in the zener diode varies from 0-50 mA. What is the maximum wattage of the diode?

• 12 W

• 6 W

• 0.6 W

• 1.2 W

A photon is incident having frequency 1 x 10 sec^-1. Threshold frequency of metal is 5 x 10¹³ sec^-1. Find the kinetic energy of the ejected electron.

• 3.3 × 10^-21 J

• 6.6 × 10^-21 J

• 3.3 × 10^-20 J

• 6.6 × 10^-20 J

Calculate I for the given circuit diagram.

• 10 A

• 5 A

• 2.5 A

• 20 A

Find the voltage drop across a capacitor connected with a resistance and a battery of 60 V in series after a long time.

• 0V

• 60 V

• 30 V

• 38 V