Which of the following statements regarding the application of electrical conduction via gases is/are correct?

Electrical conduction in gas is applied in:

(i) The identification of gases

(ii) Lighting/fluorescent tubes

(iii) Photocells

(iv) Cathode ray oscilloscope/T.V. tubes

• A. (i), (iii) and (iv) only
• B. (i), (ii) and (iv) only
• C. (ii), (iii) and (iv) only
• D. (i), (ii) and (iii) only

When an ebolite rod is rubbed with fur, it has

• A. no charge at all
• B. a negative charge
• C. a positive charge
• D. negative and positive charges

Which of the following is the dimension for impulse?

• A. MLT\(^{-1}\)
• B. MLT\(^{-2}\)
• C. MLT
• D. ML

A girl stand 80m away from a tall cliff and blows a whistle. If the speed of sound in air is 330ms^-1, how long would it take for her to hear the echo of the sound?

• A. 2.062s
• B. 0.970s
• C. 0.485s
• D. 0.242s

A man weighing 200 N runs up a staircase in 5s. If the height of the staircase is 9 m, calculate the power of the man.

• A. 1000 W
• B. 360 W
• C. 40 W
• D. 1800 W

The p.d across a parallel-plate capacitor is 10³V. If the distance between the two plates is 10cm. Calculate the magnitude of the electric field strength between the plates.

• A. 1.0 x 10⁴Vm^-1
• B. 1.0 x 10⁵Vm^-1
• C. 1.5 x 10⁵Vm^-1
• D. 2.0 x 10⁵Vm^-1

Pure silicon can be converted to a p-type by adding a controlled amount of

• A. trivalent atoms
• B. tetravalent atoms
• C. pentavalent atoms
• D. hexavalent atoms

A wire of resistivity 4.40 x 10^-5\(\Omega\) cm has a cross sectional area of 7.50 x 10^-4 cm². Calculate the length of the wire that will be required to make a 4.0\(\Omega\) resistor

• A. 82.50 cm
• B. 68.18cm
• C. 15.90cm
• D. 11.95cm

How much net work is required to accelerate a 1200 kg car from 10\(ms^{-1}\) to 15\(ms^{-1}\)

• A. 1.95
• B. 1.35
• C. 7.5
• D. 6.0

A concave mirror forms a magnified and errect image only when the object is placed

• A. at the centre of curvature
• B. at the focus
• C. between the focus and the pole of the mirror
• D. beyound the radius of curvature