An electron of charge 1.6 x 10-¹⁹C and mass 9.1 x 10-³¹kg is accelerated between two metal plates with a velocity of 4 x 10⁷m/s, the potential difference between the plates is

• A. 4.55 x 10³V
• B. 4.55 x 10²V
• C. 9.10 x 10¹V
• D. 4.55 x 10¹V

The slope of a straight-line velocity-time graph represents

• A. uniform acceleration
• B. uniform speed
• C. total distance travelled
• D. workdone

Three cells each of e.m.f 1.5 V and internal resistance 2.5Ω are connected as shown in the diagram below. Find the net e.m.f and the internal resistance

• A) 1.5V, 7.50Ω
• B) 1,5V, 0.83Ω
• C) 4.5V, 7.50Ω
• D) 4.5V, 0.83Ω

A cell of internal resistance r supplies current to a 6.0Ω resistor and its efficiency is 75%. Find the value of r.

• A. 4.5Ω
• B. 1.0Ω
• C. 8.0Ω
• D. 2.0Ω

The distance between two successive crests of a water is 1m. If a particle on the surface of the water makes two complete vertical oscillations in 1 second, calculate the speed of the wave

• A. 0.5 ms^-1
• B. 1.0 ms^-1
• C. 2.0ms^-1
• D. 3.0ms^-1

A lens of focal length 15.0 cm forms an upright image four times the size of an object. Calculate the distance of the image from the lens

• A. 11.3cm
• B. 18.8 cm
• C. 37.5cm
• D. 75.0cm

Which of the following phenomena causes capillary of liquids in tubes of narrow bore?

• A. viscosity
• B. surface tension
• C. osmosis
• D. brownian motion

What change in velocity would be produced on a body of mass 4kg if a constant force of 16 N acts on it for2 s?

• A. 0.5 ms^-1
• B. 2.0ms^-1
• C. 8.0 ms^-1
• D. 32.0 ms^-1

Which of the following is TRUE of a particle moving in a horizontal circle with constant angular velocity?

• A. The energy is costant but the linear momentum varies
• B. The linear momentum is conatant but the energy varies
• C. both energy and linear momentum are constant
• D. The speed and the linear velocity are both constant

(a) Define magnetic line of force.

(b) A wire of length 10 cm carrying a current of 4.0 A is placed between the poles of a powerful electromagnet of magnetic flux density 2.0 T. Calculate the:

(i) force on the wire when it is parallel to the field;

(ii) maximum force on the wire;

(iii) force on the wire when it makes an angle of 60° with the field.

(c) Describe how keepers can be used to preserve the magnetic strength of permanent bar magnets.

(d) A sailor observes that his mariners' compass reads N 10° W at a place where the angle of declination is N15° W. Calculate the true bearing of the place.