The diagram below represents the graph of the force applied in stretching a spiral spring against the corresponding extension produced within its elastic limit.

Using the notations on the graph, determine the:

(a) force constant of the spring;

(b) work done in stretching the spring from 10 x 10\(^{-2}\)m to 20 x 10\(^{-2}\)m.

When blue and green colours of light are mixed, the resultant colour is

• A. cyan
• B. magenta
• C. black
• D. yellow

A resistor of resistance R is connected to a battery of negligible internal resistance. If a siilar resistor is connected in series with it the

• A. effective resistance of the circuit is halved
• B. total power dissipated is doubled
• C. total current in the circuit is halved
• D. terminal voltage is halved

Which of the following electromagnetic waves has the shortest wavelength?

• A. Visible Light
• B. Ultraviolet rays
• C. Infrared rays
• D. Gamma rays

Which of the following statements about the use of radioisotopes is not correct? They are used to

• A. induce mutations in plants and animals to obtain new and improved varieties
• B. trace the paths of metabolic processes in plants and animals
• C. estmate the age of rocks
• D. locate broken bones

Cloud formation is the direct result of

• A. precipitation
• B. vaporization
• C. fusion
• D. sublimation

What is the inductance (L) of an inductor whose reactance is 1Ω at 50/ π hertz (H)?

• A. 100 H
• B. 0.01H
• C. 10H
• D. 1H

In a series R-L-C circuit at resonance, the voltages across the resistor and the inductors are 30V and 40V respectively. What is the voltage across the capacitor?

• A. 30V
• B. 40V
• C. 50V
• D. 70V

At which position should an object be placed in front of a concave mirror in order to obtain an image which is of the same size as the object?

• A. at the centre of curvature
• B. at the principal focus
• C. between the pole and principal focus
• D. between the centre of curvature and principal focus

Calculate the electric potential at a distance of 20.0cm from a point charge of 0.015C placed in air of permittivity (Take 1/4??_o as 9.0 x 10⁹ Nm²C²)

• A. 3.40x10⁶V
• B. 6.75x10⁵V
• C. 6.75x10¹²V
• D. 3.40x10⁵V