Electromagnetic Waves — Physics STD 12 Science — Question

Referring to the figure below, the effective resistance of the network is

(a) 2 r

(b) 4 r

(c) 10 r

(d) 5r/2

Electric force on an electron, in an electric field is __________ .

The permanent magnetic moment of the atoms of a material is zero. The material:

1. Must be paramagnetic.
2. Must be diamagnetic.
3. Must be ferromagnetic.
4. May be paramagnetic.

A rod of a certain metal is 1.0 m long and 0.6 cm in diameter.  Its resistance is 3.0 ×   ohm.  Another disc made of the same metal is 2.0 cm in diameter and 1.0 mm thick.  What is the resistance between the round faces of the disc

(a) 1.35 ×   ohm

(b) 2.70 ×   ohm

(c) 4.05 ×   ohm

(d) 8.10 ×   ohm

Dr. Gilbert tried to hold a brass rod by hand and induce static electricity in it by friction. Why did he fail?

A hot liquid is kept in a big room. The logarithm of the numerical value of the temperature difference between the liquid and the room is plotted against time. The plot will be very nearly:

1. A straight line.
2. A circular are.
3. A parabola.
4. An ellipse.

The peak voltage in the output of a half-wave diode rectifier fed with a sinusoidal signal without filter is 10 V. The dc component of the output voltage is

(a) 10/

(b) 10/p V

(c) 10 V

(d) 20/p V

If the refractive indices of a prism for red, yellow and violet colours be 1.61, 1.63 and 1.65 respectively, then the dispersive power of the prism will be

(a)

(b)

(c)

(d)