Current Electricity — Physics STD 12 Science — Question

In the figure, current through the 3 Ω  resistor is 0.8 ampere, then potential drop through 4 Ω  resistor is

(a) 9.6 V

(b) 2.6 V

(c) 4.8 V

(d) 1.2 V

What will be the ratio of de-Broglie wavelengths of proton and α - particle of same energy

(a) 2 : 1

(b) 1 : 2

(c) 4 : 1

(d) 1 : 4

A transformer is used to

(a) Change the alternating potential

(b) Change the alternating current

(c) To prevent the power loss in alternating current flow

(d) To increase the power of current source

PN-junction diode works as a insulator, if connected

(a) To A.C.

(b) In forward bias

(c) In reverse bias

(d) None of these

A moving charge produces:

1. Electric field only.
2. Magnetic field only.
3. Both of them.
4. None of them.

X-rays when incident on a meta

(a) Exert a force on it	(b) Transfer energy to it
(c) Transfer pressure to it	(d) All of the above

In the following arrangement y = 1.0 mm, d = 0.24 mm and D = 1.2 m. The work function of the material of the emitter is 2.2 eV. The stopping potential V needed to stop the photo current will be

(a) 0.9 V

(b) 0.5 V

(c) 0.4 V

(d) 0.1 V

In Thomson spectrograph experiment, four positive ions P,Q,R and S are situated on Y-X curve a shown in the figure

(a) The specific charge of R and S are same

(b) The masses of P and S are same

(c) The specific charges of Q and R are same

(d) The velocities of R and S are same

Two resistors R and 2R are connected in series in an electric circuit. The thermal energy developed in R and 2R are in the ratio:

1. 1 : 2.
2. 2 : 1.
3. 1 : 4.
4. 4 : 1.