2004 - JAMB Physics Past Questions and Answers - page 5

Sensitivity of a measuring instrument is given by deflection per unit current: and given that deflection = 30^o; and current (I) = 3A: then the sensitivity of the meter = ³⁰/₀ = 10.0

I wave - particle duality of matter, the momentum of sub-atomic particle is given by P = ^h/_λ where h = planck constant ; λ = wave length
=> λ = ^h/_P

In a reverse biased junction diode only a very small current flows in, carried by the minority carriers which are the negative charges in the n-semi conductor

In an R - L - C circuit resonance occurs when the inductive reactance (X_L), is equal to the capacitive reactance (X_C)
1.e X_L = X_C

The binding energy of a nucleus, is the work done or energy needed to separate completely the nucleons (protons and neutrons) apart. Again, experiment shows that the total mass of all individual nucleons is greater than that of the nucleus, in which they are together. This difference in the mass is the measure of the binding energy of the particular nucleus.

For helium	4	He,
2

it has altogether 4 nucleons 2 protons and 2 neutrons
2:H = 2 x 1.00783 = 2.01566
2:n = 2 x 1.00867 = 2.01734
∴ 2:H + 2:n = 4.03300u
But the helium nucleus has a mass of 4.00260u
∴ Binding energy = difference of nucleons and nucleus
= 4.03300U - 4.00260U = 0.03040U

Energy stored in a coil of inductance, L, and carry a current, I is given by
E = ¹/₂ L I²
= ¹/₂ x 5 x 10^-3 x 6 x 6
= 9.0 x 10^-2J

Energy stored = Ivt = current x back e.m.f x time
= 2 x 3 x 0.4
= 2.4J