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

A cylindrical bar magnet is rotated about its axis (Fig). A wire is connected from the axis and is made to touch the cylindrical surface through a contact. Then,

An electromagnet:

A ray of light is incident at an angle of 60° on one face of a prism of angle 30°. The ray emerging out of the prism makes an angle of 30° with the incident ray. The emergent ray is

(a) Normal to the face through which it emerges

(b) Inclined at 30° to the face through which it emerges

(c) Inclined at 60° to the face through which it emerges

(d) None of these

A galvanometer of resistance 36 W is changed into an ammeter by using a shunt of 4 W.  The fraction f₀ of total current passing through the galvanometer is

(a)

(b)

(c)

(d)

Two samples A and B are initially kept in the same state. Sample A is expanded through an adiabatic process and the sample B through an isothermal process. The final volumes of the samples are the same. The final pressures in A and B are p_A and p_B respectively.

1. p_A > p_B
2. p_A = p_B
3. p_A < p_B
4. The relation between p_A and p_B cannot be deduced.

An electric dipole has a pair of equal and opposite point charges q and –q separated by a distance 2x. The axis of the dipole is:

Which of the following particles will describe the smallest circle when projected with the same velocity perpendicular to a magnetic field?

1. Electron
2. Proton
3. He⁺
4. Li⁺

A wire 100 cm long and 2.0 mm diameter has a resistance of 0.7 ohm, the electrical resistivity of the material is

(a) 4.4	(b) 2.2
(c) 1.1	(d) 0.22

A coil having N turns is wound tightly in the form of a spiral with inner and outer radii a and b respectively. When a current I passes through the coil, the magnetic field at the centre is

(a)

(b)

(c)

(d)