Correct Answer: D) remains constant

Correct Answer: A. longer than \(10^{-6} m\).

Explanation

The range of wavelengths for infrared waves is given as \(10^{-3}\) m to \(10^{-6}\)m. This means that the wavelength of the radiation is longer than \(10^{-6} m\) but shorter than \{10^{-3} m\). Therefore, the only correct option is that the wavelength is longer than \(10^{-6} m\).

Correct Answer: D. Its frequency changes.

Explanation

Refraction occurs when light travels from one medium to another which changes the speed at which the light travels.

This causes light to bend upon incidence with the interface of a new material.

Angle of refraction is smaller than angle of incidence when light ray travels from rarer medium to denser medium.

I.e light can either refract towards the normal(when slowing down while crossing the boundary) or away from the normal (when speeding up while crossing the boundary).

When light undergoes refraction, its frequency remains the same.

Correct Answer: A. 1,050W

Explanation

n = \(\frac{sin i}{sin r}\)

1.5 = \(\frac{sin \theta}{sin(190 - \theta)} = \frac{sin \theta}{cos theta} = \tan \theta\)

Hence, 0 = tan\(^{-1}\) 1.5 = 56.31\(^o\)

Correct Answer: B. 0.2J

Correct Answer: B. 6.0ms^-1

Explanation

v = \(\sqrt{U^2} + 2as = \sqrt{0^2} + 2 \times 2 \times 9 = 6\)m/s

Correct Answer: D. xylophone

Correct Answer: C. earth's magnetic flux is entirely horizontal at a place where the magnetic dip is zero

Explanation

(a) Elecromotive force is the energy needed to take a unit positive charge round a circuit in which a cell is connected. Or The energy per unit charge transformed in the cell. Or e.m.f is the p.d across the terminals of the cell or battery or generator in an open circuit.

(b)(i) The principle of operation of a potentiometer is based on the fact that the p.d across the wire is directly proportional to the length of the wire.V \(\alpha\) L

where V = p.d across the wire.

L = length of the wire.

(ii) Advantages of potentiometer over voltmeter in measuring p.d are:

(1) It is more sensitive.

(2) It is more accurate.

(3) It eliminates error due to internal resistance of the cell.

(c)(i) Labelled sketch of a Gold leaf electroscope:

(ii) Uses of Gold leaf electroscope are:

(1) To detetct the nature of electrostatic charge.

(2) To detect electrostatic charge.

(3) To determine the magnitude of the induced charges.

(d)(i) The mode of action of magnetic relay relies on the principle of electromagnetic induction. A small current passing through one circuit controls another circuit containing devices which require larger current.

(ii) Factors affecting the magnitude of induced e.m.f in a coil are:

(1) the number of turns in the coil.

(2) the magnetic field strength.

(3) the cross-sectional area of the coil.

(4) the speed of rotation of the coil.

(iii) F = IBLsin\(\theta\)

force per unit length

\(\frac{F}{L}\) = IBsin\(\theta\)

= 5 x 2.0 x 10\(^{-3}\) x sin30

= 5.0 x 10\(^{-3}\)Nm\(^{-1}\)