Electric Charges and Fields — Physics STD 12 Science — Question

The magnetic susceptibility is negative for:

Due to the earth's magnetic field, charged cosmic ray particles

(a) Require greater kinetic energy to reach the equator than the poles

(b) Require less kinetic energy to reach the equator than the poles

(c) Can never reach the equator

(d) Can never reach the poles

By ammeter, which of the following can be measured

(a) Electric potential

(b) Potential difference

(c) Current

(d) Resistance

The plate current in a triode is given by    where I_p, V_p and V_g are the values of plate current, plate voltage and grid voltage, respectively. What are the triode parameters m, r_p and g_m for the operating point at   and  ?

(a) 10, 16.7 kW, 0.6 m mho	(b) 15, 16.7 kW, 0.06 m mho
(c) 20, 6 kW, 16.7 m mho	(d) None of these

Give electronic configuration of silicon.

Three charges 2q, -q, -q  are located at the vertices of an equilateral triangle. At the centre of the triangle

(a) The field is zero but potential is non-zero	(b) The field is non-zero but potential is zero
(c) Both field and potential are zero	(d) Both field and potential are non-zero

If an observer is walking away from the plane mirror with 6m/sec.  Then the velocity of the image with respect to observer will be

(a) 6 m/sec

(b) -6 m/sec

(c) 12 m/sec

(d) 3 m/sec

Two lenses are placed in contact with each other and the focal length of combination is 80 cm. If the focal length of one is 20 cm, then the power of the other will be

(a) 1.66 D

(b) 4.00 D

(c) –1.00 D

(d) – 3.75 D

The lines of forces due to earth's horizontal component of magnetic field are

(a) Parallel straight lines	(b) Concentric circles
(c) Elliptical	(d) Parabolic

What is the nature of equipotential surfaces in case of a positive point charge?