Correct Answer: B. work

Explanation

P = \(\frac{N}{m^2}\)

V = m

PV = Nm unit of work

Explanation

a)(i) Interference occurs in all kinds of waves i.e. longitudinal or transverse, while polarisation occurs only in transverse waves.

(ii) - In sun glasses to reduce the intensity of light.

- To produce polarised light.

- To produce three dimensional pictures.

Correct Answer: A. 2g

Explanation

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Explanation

(a)(i) Reactance is the opposition to the flow of a.c offered by a capacitor or an inductor or both.

(ii) Impedance is the overall opposition of a mixed circuit containing a resistor, an inductor and/or a capacitor.

(b) (i) Emf is induced because the coil rotates at a steady speed about a fixed axis in the magnetic field of the elctromagnet, it cuts through the magnetic lines of force.

(ii) The direction of current is reversed in each half of the rotation of the coil.

(iii) The law used to determine the direction of the induced current is Lenz's law. It states that the direction of the induced current is such as to oppose the change producing it.

(iv) The induced e.m.f can be increased by any two of the following: increased speed of rotation, efficient core design, increased number of turns in the coil and increased area of coil.

(c) E = Power x Time

= 6 x 5 x 60

=1800J

Correct Answer: B. 3.0N

Explanation

volume of object = \(\frac{400 \times 10^{-2}}{600}\)

= 0.00067m³

volume of paraffin displaced = \(\frac{1}{2}\) x 0.00067

= 0.00034m³

mass of paraffin = 900 x 34 x 10^-5

= 0.3kg

weight of paraffin = 0.3 x 10

= 3N = upthrust = tension in the string

Correct Answer: A. Infra-red rays

Explanation

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Correct Answer: D. 2V3N

Explanation

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Correct Answer: B. 20 ms^-2

Explanation

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Explanation

Any image that can be formed on a screen are called real image. Such images are formed by light rays emanating from the object, when reflected and/or refracted by devices such as lenses and mirrors converge at some specific point. In contrast there are other images which are formed by the rays of light reaching the observer appearing to converge at some point. This happens when the rays reaching the observer are diverging and when the line of these rays are projected backward. Such images, which cannot be formed on a screen, are called virtual image.

Explanation

Materials for making optical fibre are Glass, Polycarbonate, Teflon sheath, Silica, quartz, Silicon, Sapphire. Feromagnetic