Explanation

(a) Surface tension is the force per unit length acting in the surface at right angles to one side of a line drawn in the surface of a liquid. It can be defined as the property of a liquid that makes it behave as if its surface is an elastic skin.

(b) Methods of reducing surface tension are by adding:

- Soap

- alcohol

- oil

- detergent

- increasing the temperature.

Correct Answer: B. 42.5nC

Explanation

A= \(0.8m^2\) d= 20mm =\(\frac{20}{1000}\) = 0.02m

v =120v; \(ε_oA\)= \(8.85 × 10^-12 fm^-1\)

C = \(\frac{ε_oA}{d}\)

C =\(\frac{8.85 × 10^-12×0.8}{0.02}\)

C= \(3.54 × 10^-10 F\)

Q= CV

⇒ \(3.54 × 10^-10\) × 120 = \(4.25×10^-8c\)

Q=\(42.5 × 10^-9c\) = 42.5nC

A= \(0.8m^2\) d= 20mm =\(\frac{20}{1000}\) = 0.02m

v =120v; \(ε_oA\)= \(8.85 × 10^-12 fm^-1\)

C = \(\frac{ε_oA}{d}\)

C =\(\frac{8.85 × 10^-12×0.8}{0.02}\)

C= \(3.54 × 10^-10 F\)

Q= CV

⇒ \(3.54 × 10^-10\) × 120 = \(4.25×10^-8c\)

Q=\(42.5 × 10^-9c\) = 42.5nC

Correct Answer: C. III & IV

Explanation

Correct Answer: A. reducing the mass of the pulley

Correct Answer: D) 5 cm

Correct Answer: C) Magenta

Explanation

(a) Applications of electrolysis:

— Electrotyping

— Electroplating

— Purification of metals

— Extraction of metals

— Callibration of ammeter

(b) It means that when a charge of one coulomb IC is passed through a copper voltameter 3.3 x 10\(^{-7}\) kg of copper is on the cathode.

Correct Answer: B. 0^o

Correct Answer: A. helioscope

Explanation

A helioscope is an instrument used for observing the sun and sunspots.

The helioscope was first used by Benedetto Castelli and refined by Galileo Galilei.