The ratio of the de-Broglie wavelength of an α-particle and a proton of same kinetic energy is

• 1 : 2

• 1 : 1

• $1 : \sqrt{2}$

• 4 : 1

Which of the following is not conserved in nuclear reaction ?

• Total energy

• Mass number

• Number of fundamental particles

• Nucleon number

The number of α-particles and β-particles respectively emitted in the reaction  ₈₈A¹⁹⁶  →  ₇₈B¹⁶⁴ are

• 8 and 8

• 8 and 6

• 6 and 8

• 6 and 6

The counting rate observed from a radioactive source at t = 0 s was 1600 count/s and at t = 8 s it was 100 counts/s. The counting rate observed as counts per second at t = 6 s, will be

• 400

• 300

• 250

• 200

If D_e, D_b and D_c are the doping levels of emitter, base and collector respectively of a transistor, then

• D_e = D_b = D_c

• D_e < D_b = D_c

• D_e > D_c > D_b

• D_e < D_b < D_c

The relation between α and β parameters of a transistor is

• $\mathrm{\alpha } = \frac{1 + \mathrm{\beta }}{\mathrm{\beta }}$

• $\mathrm{\alpha } = \frac{1 - \mathrm{\beta }}{\mathrm{\beta }}$

• $\mathrm{\alpha } = \frac{\mathrm{\beta }}{1 + \mathrm{\beta }}$

• $\mathrm{\alpha } = \frac{\mathrm{\beta }}{1 - \mathrm{\beta }}$

67.

A p-n junction in series with a resistance of 5 km is connected across a 50 V DC source. If the forward bias resistance of the junction is 50 Ω, the forward bias current is

                      

• 8.8 mA

• 1 mA

• 9.9 mA

• 20 mA

A transistor connected at common-emitter mode contains load resistance of 5 kΩ and an input resistance of 1 kΩ. If the input peak voltage is 5 mV and the current gain is 5O, find the voltage gain

• 250

• 500

• 125

• 50

If n₁ and n₂ are the refractive indices of the core and the cladding respectively of an optic fibre, then

• n₁ = n₂

• n₁ < n₂

• n₂  <  n₁

• n₂ = 2n₁

If a radio receiver amplifies all the signal frequencies equally well, it is said to have high

• fidelity

• distortion

• sensibility

• sensitivity