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21.

The V-I characteristic of a diode is shown in the figure. The ratio of forward to reverse bias resistance is:

942021564_zevneojfy4iv-q.jpeg


A) 10

B) $10^{-6}$

C) $10^{6}$

D) 100



22.

The magnetic field in a travelling electromagnetic wave has a peak value of 20 nT. The peak value of electric field strength is


A) 3 V/m

B) 6 V/m

C) 9 V/m

D) 12 V/m



23.

The velocity of water in a river is 18 km/hr near the surface. If the river is 5 m deep, find the shearing stress between the horizontal layers of water.-The co-efficient of viscosity of water = 10-2 poise.

 


A) $10^{-1}N/m^{2}$

B) $10^{-2}N/m^{2}$

C) $10^{-3}N/m^{2}$

D) $10^{-4}N/m^{2}$



24.

The horizontal component of the earth's magnetic field is 3.6x10-5 tesla where the dip angle is 60º. The magnitude of the earth's magnetic field is


A) $2.8\times 10^{-4}$ tesla

B) $2.1\times 10^{-4}$

C) $7.2\times 10^{-5}$

D) $3.6\times 10^{-5}$



25.

Two batteries of e.m.f 4V and 8V with internal resistance 1 Ω and 2Ω  are connected in a circuit with a resistance of 9 Ω as shown in figure. The current and potential difference between the points P and Q are

842021764_1.PNG


A) 1/3 A and 3 V

B) 1/6A and 4 V

C) 1/9 A and 9V

D) 1/12 A and 12V



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