Moving Charges and Magnetism — Physics STD 12 Science — Question

The combination of ‘NAND’ gates shown here under (figure) are equivalent to

(a) An OR gate and an AND gate respectively

(b) An AND gate and a NOT gate respectively

(c) An AND gate and an OR gate respectively

(d) An OR gate and a NOT gate respectively.

In the following diagram the work done in moving a point charge from point P to point A, B and C is respectively as W_A, W_B and W_C , then

(a) WA = WB = WC

(b) WA = WB = WC = 0

(c) WA > WB > WC

(d) WA < WB < WC

A transformer is employed to

(a) Obtain a suitable dc voltage	(b) Convert dc into ac
(c) Obtain a suitable ac voltage	(d) Convert ac into dc

A rectangular coil 20 cm × 20 cm  has 100 turns and carries a current of 1 A. It is placed in a uniform magnetic field       B  = 0.5 T with the direction of magnetic field parallel to the plane of the coil. The magnitude of the torque required to hold this coil in this position is

(a) Zero

(b) 200 N-m

(c) 2 N-m

(d) 10 N-m

Refer to the arrangement of charges in Fig. and a Gaussian surface of radius R with Q at the centre. Then:

If 10% of a radioactive material decays in 5 days, then the amount of original material left after 20 days is approximately

(a) 60%

(b) 65%

(c) 70%

(d) 75%

Spectrum of sunlight is an example for:

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

Mark the correct options: