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

A achromatic combination is made with a lens of focal length f and dispersive power ω with a lens having dispersive power of 2ω. The focal length of second will be

(a) 2f

(b) f/2

(c) -f/2

(d) – 2 f

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The plates of a parallel plate condenser are pulled apart with a velocity v. If at any instant their mutual distance of separation is d, then the magnitude of the time of rate of change of capacity depends on d as follows

(a)

(b)

(c)

(d) d

The hysteresis cycle for the material of permanent magnet is:

In a triode valve

(a) If the grid voltage is zero then plate current will be zero

(b) If the temperature of filament is doubled, then the thermionic current will also be doubled

(c) If the temperature of filament is doubled, then the thermionic current will nearly be four times

(d) At a definite grid voltage the plate current varies with plate voltage according to Ohm’s law

Which of the following plots may represent the thermal energy produced in a resistor in a given time as a function of the electric current

(a) a

(b) b

(c) c

(d) d

Least doped region in a transistor

(a) Either emitter or collector

(b) Base

(c) Emitter

(d) Collector

Figure represents two simple harmonic motions. The parameter which has different values in the two motions is:

1. Amplitude.
2. Frequency.
3. Phase.
4. Maximum velocity.

In Young's double slit experiment how many maximas can be obtained on a screen (including the central maximum) on both sides of the central fringe if λ = 2000 and d = 7000  

(a) 12

(b) 7

(c) 18

(d) 4

A convex lens of focal length 0.5 m and concave lens of focal length 1 m are combined. The power of the resulting lens will be

(a) 1 D

(b) – 1 D

(c) 0.5 D

(d)  – 0.5 D