The magnification produced by a astronomical telescope for normal adjustment is 10 and the length of the telescope is 1.1 m. The magnification, when the image is formed atleast distance of distinct vision is

• 6

• 18

• 16

• 14

Two slits are separated by a distance of 0.5 mm and illuminated with light of wavelength λ = 6000 A^o. If the screen is placed at 2.5 m from the slits. The distance of the third bright fringe from the centre will be

• 1.5 mm

• 3 mm

• 6 mm

• 9 mm

33.

Assertion:  A ray of light is incident from outside on a glass sphere surrounded by air. This ray may suffer total internal reflection at second interface.

Reason:  If a ray of light goes from denser to rarer medium, it bends away from the normal.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Assertion:  Two point coherent sources of light S₁ and S₂ are placed on a line as shown. P and Q are two points on that line. If at point P maximum intensity is observed then maximum intensity should also be observed at Q.

Reason:  In the figure of assertion the distance $\left|{\mathrm{S}}_1\mathrm{P} - {\mathrm{S}}_2\mathrm{P} \right|$ is equal to distance $\left| {\mathrm{S}}_2\mathrm{Q} - {\mathrm{S}}_1\mathrm{Q} \right|$.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

In a Fraunhofer diffraction at single slit of width  d  with incident light of wavelength 5500 A^o,  the first minimum is observed, at angle 30°. The first secondary maximum is observed at an angle θ = 

• sin^-1 $\frac{1}{\sqrt{2}}$

• sin^-1$\frac{1}{4}$

• sin^-1$\frac{3}{4}$

• sin^-1$\frac{\sqrt{3}}{2}$

The intensity ratio of the maxima and minima in an interference pattern produced by two coherent sources of light is 9 : 1. The intensities of the used light sources are in ratio

• 3 : 1

• 4 : 1

• 9 : 1

• 10 : 1

The two coherent sources with intensity ratio β produce interference. The fringe visibility will be

• $\frac{2 \sqrt{\mathrm{\beta }}}{1 + \mathrm{\beta }}$

• 2 β

• $\frac{2}{\left(1 + \mathrm{\beta }\right)}$

• $\frac{\sqrt{\mathrm{\beta }}}{1 + \mathrm{\beta }}$

Assertion: In YDSE bright and dark fringe are equally spaced.

Reason: It only depends upon phase difference.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

In a certain double slit experimental arrangement, interference fringes of width 1 mm each are observed when light of wavelength 5000 A^o  is used. Keeping the setup unaltered, if the source is replaced by another of wavelength 6000 A^o, the fringe width will be

• 1.2 mm

• 0.5 mm

• 1 mm

• 1.5 mm

Assertion:  In a common emitter transistor amplifier, the input current is much less than the output current than output impedance. 

Reason:  The common emitter transistor amplifier has higher input impedance than output impedance.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.