41.

The refractive index of glass is 1.520 for red light and 1.525 for blue light. Let D₁ and D₂ be an of minimum deviation for red and blue light respectively in a prism of this glass. Then

• D₁ > D₂

• D₁ < D₂

• D₁ = D₂

• D₁ = D₂

A thermocouple is made from two metals, Antimony and Bismuth. If one junction of the couple is kept hot and the other is kept cold then, an electric current will

• flow from Antimony to Bismuth at the cold junction

• flow from Antimony to Bismuth at the hot junction

• flow from Bismuth to Antimony at the cold junction

• flow from Bismuth to Antimony at the cold junction

The time by a photoelectron to come out after the photon strikes is approximately

• 10⁻¹ s

• 10⁻⁴ s

• 10−¹⁰ s

• 10−¹⁰ s

An alpha nucleus of energy 1 /2 mv² bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional to 

• 1/Ze

• v²

• 1/m

• 1/m

The energy spectrum of β-particles [number N(E) as a function of β-energy E] emitted from a radioactive source is

When ₃Li⁷ nuclei are bombarded by protons, and the resultant nuclei are ₄Be⁸ , the emitted particles will be

• neutrons

• alpha particles

• beta particles

• beta particles

A solid which is transparent to visible light and whose conductivity increases with temperature is formed by

• Metallic binding

• Ionic binding

• Covalent binding

• Covalent binding

If the ratio of the concentration of electrons that of holes in a semiconductor is 7 /5 and the ratio of currents is 7/4, then what is the ratio of their drift velocities?

• 4/7

• 5/8

• 4/5

• 4/5

In a common base mode of a transistor, t collector current is 5.488 mA for an emit current of 5.60 mA. The value of the base current amplification factor (β) will be

• 48

• 49

• 50

• 50

The anode voltage of a photocell is kept fixed. The wavelength λ of the light falling on the cathode is gradually changed. The plate current I of the photocell varies as follows