(a)  State two ways in which one can increase the strength of an electromagnet. (2 mks)

(b)  The following figure shows a conductor placed in a magnetic field.  Indicate on the diagram the direction of motion of part AB of the conductor.         (2mks)

(c) A cell drives a current of 5A through a 1.6W resistor.  When connected to a 2.8W resistor, the current that flows in 3.2A.  Find E and r for the cell.             (4 mks)

(d) Calculate the length of a nichrome resistance wire of cross-sectional area 7 ´10ˉ⁸m² required to make a resistor of 10 ohms.  (Take resistivity of nichrome = 1.10 ´ 10ˉ⁶Wm).   (3 mks)

(e)   In figure below, calculate the p.d across resistor R.             (2 mks)

        Current in the primary circuit.                  (2 mks)

A transformer with 2000 turns in the primary circuit and 150 turns in the secondary circuit has its primary circuit connected to a 800V a.c. source.   It is found that when a heater is connected to the secondary circuit it produces heat at the rate of 1000W.  Assuming 100% efficiency, determine the:

(i)    Voltage in the secondary circuit.              (2 mks)

(ii)      Current in the secondary circuit.             (1 mk)

(iii)  State the type of transformer represented above.                (1 mk)

 (b)  (i)  State the reason why long distance power transmission is done at a very high voltage and using thick cables.         (1 mk)

(ii) Calculate the cost of using the following appliances in one month (30 days) of the company rate is Ksh.9.50 per unit.

I           A 2000W water heater for 2 hours per day.

II          A 75W bulb for 10 hours per day.

III        An 1500W electric iron for 1 hour per day.                    (3 mks)

(iii) Find the total monthly bill for the above household if in addition to the energy consumed, the power company charges each consumer.

I           A standing charge of Ksh.200.

II          Fuel cost levy at 70 cents per unit.                  (2 mks)

Kai noticed that any time he a light from his car and close the door holding the metallic hand he get a slight shock. Explain.             (2mks)

An electric heater rated 240V, 3000W is to be connected to a 240V mains supply, through a 10A fuse.  Determine whether the fuse is suitable or not.     (3 mks)

(a) Distinguish between a transverse and a longitudinal wave.                   (1 mk)

(b) Determine the frequency of the wave shown below.       (2 mks)

(c) State one reason why ultrasound is preferred to audible sound in echo-sounding.       (1 mk)

Distinguish between a transformer and induction coil.          (2mks)

The following are electromagnetic waves. Arrange them according to their increasing frequency. Gamma rays, microwaves, ultra-violet, TV waves and blue light.         (1mk)

An appliance is rated 2.5KW, 240V a.c 50Hz. Explain the meaning of this rating on this appliance.                    (2mks)

The figure below shows a circuit diagram with cells in parallel. Each cell has e.m.f of 1.5V and internal resistance of 0.5Ω and the resistance of the bulb is 6Ω each. Determine the ammeter reading when the switch is closed.                  (3mks)

Why is a convex mirror better than plane mirror when used as a driving mirror?          (1 mk)