1999 - JAMB Physics Past Questions and Answers - page 3

The maximum current drawn by the cooker is given by;

I = P/V

∴ I = 3000/200

I = 15A

Thus the most suitable fuse to be used is a 10A fuse

Shunt resistance is usually given as

R = igrg/(I - ig)

Where R = 0.05Ω

rg = 5Ω

I = 2M

∴ ig = IR/(rg + R)

= (2 x 0.05)/(5 + 0.05)

= 0.10/5.05

= 0.0198A

= 19.8mA

= 20mA

Inductive reactance X_L = 2πfL

∴ 2πfL = 2000Ω

then f = 2000Ω/2 x π x 10

f = 100/πHz

Gamma rays are electromagnetic radiation of nuclear origin; they are produced from energy changes which occur within the nucleus of atoms

Energy of a particle is given by

E = hf = hV/λ (since V = fxλ)

But in terms of mass M, E = ∆MV²

∴ ∆MV² = hV/λ

∆MV = h/λ

∴ V = h/λ∆M

V = 6.63 x 10^-34/(10^-27 x 10^-8)

V = 6.63 x 10^-34/10^-35

V = 6.63 x 10^-34+35

V = 6.63 x 10

V = 66.3ms^-1

At resonance, inductive reactant X_L is equal to the capacitive reactance X_C

i.e. X_L = X_C

and X_L = V_L/I_L

and X_C = V_C/I_C

Again since the components are in series, the same current flows in the series arrangment

i.e. I_L = I_C

at resonance, V_L/I_L = V_C/I_C

∴ V_L = V_C

= 40V

²³₁₁Na + Proton → ^p_qX + alpha particle

Represent;
²³₁₁Na + ¹₁P → ^p_qX + ⁴₂He

Thus from the above equations, p = 20 and q = 10