51.

The width of the depletion region in a p-n junction diode is

• increased by reverse bias

• increased by forward bias

• decreased by reverse bias

• independent of the bias voltage

When the transistor is used as an amplifier

• Emitter-base junction must be reverse biased, Collector-base junction must be forward

• Emitter-base junction must be forward biased, Collector-base Junction must be forward biased

• Emitter-base junction must be reverse biased, Collector-base junction must be reverse biased

• Emitter-base junction must be forward biased, Collector-base junction must be reverse biased

Which of the following is not made by quarks ? 

• Neutron

• Positron

• Proton

• $\mathrm{\pi }$-meson

Which one of the following is not correct ?

• In forward biased condition diode conducts

• If the packing fraction is negative, the elelment is stable

• B1nd1ng energy is the energy equivalent to mass defect

• Radioactive element can undergo spontaneous fission

The output of an OR gate is connected to both the inputs of a NAND gate. The combination will serve as

• AND gate

• NOT gate

• NAND gate

• NOR gate

A and B are the two radioactive elements. The mixtue of these elements show a total activity of 1200 disintergrations/mmute. The half-life of A is 1 day and that of B is 2 days. What will be the total activity after 4 days? Given, the initial number of atoms in A and B are equal

• 200 dis/min

• 250 dis/min

• 500 dis/min

• 150 dis/min

The binding energy/nucleon of deuteron (₁H²) and the helium atom (₂He⁴) are 1.1 MeV and 7 MeV respectively. If the two deuteron atoms fuse to form a single helium atom, then the energy released is

• 26.9 MeV

• 25.8 MeV

• 23.6 MeV

• 12.9 MeV

Pick out the wrong statement from the following

• Lateral shift increases as the angle of incidence increases

• Lateral shift increases as the value of refractive index increases

• Normal shift decreases as the value of refractive index increases

• Both normal shift and lateral shift are directly proportional to the thickness of the medium

The refraction through the prisms are as shown. Pick out the wrong statement from the following. Path of the light ray in

• a is correct if n₂ > n₁ and n₂ > n₃

• b is correct if n₁ = n₂ and n₂ > n₃

• c is correct if n₂ < n₁ and n₂ = n₃

• d is correct if n₁ > n₂ and n₂ < n₃

The distance between an object and its image produced by a converging lens is 0.72 m. The magnification is 2. What will be the magnification when the object is moved by 0.04 m towards the lens ?

• 2

• 4

• 3

• 6