A small amount of air is introduced into the vacuum above the mercury in a mercury barometer tube. The mercury level goes down because the air molecules

• A. heat the mercury and make it expand
• B. increase the pressure above the mercury.
• C. cool the mercury and make it contract.
• D. decrease the pressure above the mercury

(a) List two properties of cathode rays

(b) Explain how the intensity and energy of cathode rays may be increased

Using the diagram below, calculate the effective capacitance of the circuit

• A. 1.56μF
• B. 3.00μF
• C. 3.71μF
• D. 9.00μF

A girl stands on a scale in a lift. If the reading on the scale is less than her weight, then the lift is moving

• A. upward at uniform speed
• B. upward with uniform acceleration
• C. downward with uniform speed
• D. downward with uniform acceleration

A progressive wave equation is represented by y = a sin (150 πt - πt/4). if the phase difference of a progressive wave is 45^o, the value of x in the equation is

• A) 3 cm
• B) 4 cm
• C) 1 cm
• D) 2 cm

Two objects P and Q of masses 100kg and 20kg respectively are 1.2m apart on a horizontal surface. Calculate the net gravitational force acting on Q. \([G= 6.67 \times 10^{-11} Nm^{2}kg^{-2}]\)

• A. \(1.11\times 10^{-7} N\) towards P
• B. \(1.11\times 10^{-7} N\) towards Q
• C. \(9.26\times 10^{-8} N\) towards P
• D. \(9.26\times 10^{-8} N\) towards Q

During the electrolysis of copper (II) tetraoxosulphate (VI) solution, a steady current of 4.0 x 10\(^2\) A flowing for one hour liberated 0.48 g of copper. Calculate the mass of copper liberated by one coulomb of charge.

Which of the following items can be used to compare the relative magnitudes of electric charges on two bodies?

• A. ebonite rod
• B. gold leaf electroscope
• C. proof plane
• D. the electrophorus

A car accelerate uniformly from rest at 4 ms^-2. How far will it travel in the fifth complete second?

• A) 100 m
• B) 50m
• C) 32 m
• D) 18 m

The limiting frictional force between two surfaces depends on

I. the cohesive force of the material

II. the nature of the surfaces in contact

III. the relative velocity between the surfaces

• A. I only
• B. II only
• C. III only
• D. I & IV only