2003 - JAMB Physics Past Questions and Answers - page 4

From the above diagram the widest separation is given by Blue and red

At minimum deviation, it is observed that light passes symmetrically through, the prism such that the angle of incidence (i^o) is angle to the angle of emergency (e^o).(i/e I^o = e^o)

116 days = 4 half - lives

Thus, after 4 half lives the fraction left of any radioactive materials is given by (¹/₂)⁴ = ¹/₁₆

∴ Count rate / amount left = ¹/₁₆ x ⁸⁰⁰/₁

= 50 count / min

The induced voltage = time rate of change of magnetic flux

But ∅_B = Magnetic Flux

= Magnetic Induction (B) x (A)

= 0.4T x 0.4m²

= 0.16 volt second

= 0.16 x 10 x 50

= 80 volts

the force on a moving charge in a magnetic field is given by: F = q V β sin θ

and this force is maximum when θ = 90^o, during which sin 90^o = 1: and for sinθ = 0.5, θ = 30^o

The stopping potential is the potential required to stop the most energetic photo-emitted electron. From the relation e Vs = K.E,_(max) where e is the electron charge, and Vs is the stopping potential => e x Vs = 0.34eV

∴ Vs = (0.34eV) / e = 0.34V

∴ stopping potential = 0.34V

An a.c current is usually expressed as I = Io sin wt; and comparing this with the given current I = 10sin (120π)t, => Io = 10.

and power in an a.c circuit is given as:

P = I²R

= (10² x 12)

= 1200W

Experiment shows that increase in temperature increases the resistance of a pure metal but decreases the resistance of pure semiconductor