2022 - JAMB Physics Past Questions and Answers - page 2

Distilled water is free from electrolytes; it does not contain any salts, minerals or acids and hence doesn't have any conducting substance in it. In other words, it is a poor conductor of electricity.

the amount left undecayed = A

the initial amount = A0

the number of half-lives that passed in a period of time = t:

\(\frac{1}{2^n} * A_0  = A\)

\(\frac{1}{2^n} * 120 = 15\)

\(\frac{1}{2^n}\) = \(\frac{15}{120}\)

\(\frac{1}{2^n}\) = \(\frac{1}{8}\)

\(\frac{1}{2^n}\) = \(\frac{1}{2^3}\)

\(2^n = 2^3\) 

n = 3
6days/3 = 2 days

Because the refractive index of water is greater than that of air the athlete's legs appear to be short while standing in the pool due to refraction.

v = f λ

v = 312 x 1.10

= 343.2m/s

As the surface area of the plates increases, capacitance increases because larger plates provide greater capacity to store electric charge.

An electromagnetic relay is an electrically operated switch that uses a magnet to turn the switch on or off.

According to the kinetic molecular model in gases, gas particles are in constant motion and exhibit perfectly elastic collisions.

The main postulates of the theory are:

(1) the particles in a gas are in constant, random motion

2) the combined volume of the particles is negligible

(3) the particles exert no forces on one another

(4) any collisions between the particles are completely elastic

(5) the average kinetic energy of the particles is proportional to the temperature in kelvins

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Energy = power x time

Power = voltage x current. 

Energy = voltage x current x time

Energy = 40 x 0.5 x 60 x 2

= 2,400j

Electrons tend to concentrate on the location with more curvature, that is, sharp edges.