Semiconductor Electronic: Material, Devices And Simple Circuits — Physics STD 12 Science — Question

Consider the following statements:

1. An emf can be induced by moving a conductor in a magnetic field.
2. An emf can be induced by changing the magnetic field.

1. Both A and B are true.
2. A is true but B is false.
3. B is true but A is false.
4. Both A and B are false.

A metal surface of work function 1.07eV is irradiated with light of wavelength 332nm. The retarding potential required to stop the escape of photo electron is:

A source of e.m.f. E = 15 V and having negligible internal resistance is connected to a variable resistance so that the current in the circuit increases with time as i = 1.2 t + 3. Then, the total charge that will flow in first five second will be(a) 10 C(b) 20 C(c) 30 C(d) 40 C

Three specimens A, B, C of same radioactive element has activities 1 microcurie, 1 rutherford and 1 becquerel respectively. Which specimen has maximum mass?

In a PNP transistor the base is the N-region. Its width relative to the P-region is (a) Smaller(b) Larger(c) Same (d) Not related

A Daniel cell is balanced on 125 cm length of a potentiometer wire. Now the cell is short-circuited by a resistance 2 ohm and the balance is obtained at 100 cm. The internal resistance of the Daniel cell is(a) 0.5 ohm(b) 1.5 ohm(c) 1.25 ohm(d) 4/5 ohm

In Young’s experiment, the distance between slits is 0.28 mm and distance between slits and screen is 1.4 m. Distance between central bright fringe and third bright fringe is 0.9 cm. What is the wavelength of used light (a) 5000 Å(b) 6000 Å(c) 7000 Å(d) 9000 Å

The number of electrons made available for conduction by dopant atoms depends strongly upon