Which of the following statement is correct?

Time taken by light to travel in two different materials $$A$$ and $$B$$ of refractive indices $${\mu }_A$$ and $${\mu }_B$$ of same thickness is $$t_1$$ and $$t_2$$ respectively. If $$t_2-t_1=5\times 10^{-10}$$ s and the ratio of $${\mu }_A$$ to $${\mu }_B$$ is $$1:2$$. Then, the thickness of material, in meter is: (Given $$v_{\mathrm{A}}$$ and $$v_{\mathrm{B}}$$ are velocities of light in $$A$$ and $$B$$ materials respectively.)

For an object placed at a distance 2.4 m from a lens, a sharp focused image is observed on a screen placed at a distance 12 cm from the lens. A glass plate of refractive index 1.5 and thickness 1 cm is introduced between lens and screen such that the glass plate plane faces parallel to the screen. By what distance should the object be shifted so that a sharp focused image is observed again on the screen?

Light travels in two media $$M_1$$ and $$M_2$$ with speeds $$1.5\times 10^8{\mathrm{ms}}^{-1}$$ and $$2.0\times 10^8{\mathrm{ms}}^{-1}$$ respectively. The critical angle between them is :

A microscope was initially placed in air (refractive index 1). It is then immersed in oil (refractive index 2). For a light whose wavelength in air is $$\lambda$$, calculate the change of microscope's resolving power due to oil and choose the correct option.

As shown in the figure, after passing through the medium 1 . The speed of light $$v_2$$ in medium 2 will be : $$($$ Given $$\mathrm{c}=3\times 10^8{\mathrm{ms}}^{-1}$$ )

In normal adujstment, for a refracting telescope, the distance between objective and eye piece is $$30\mathrm{cm}$$. The focal length of the objective, when the angular magnification of the telescope is 2 , will be :

The power of a lens (biconvex) is $$1.25{\mathrm{m}}^{-1}$$ in particular medium. Refractive index of the lens is 1.5 and radii of curvature are $$20\mathrm{cm}$$ and $$40\mathrm{cm}$$ respectively. The refractive index of surrounding medium:

Light enters from air into a given medium at an angle of $$45^{\circ }$$ with interface of the air-medium surface. After refraction, the light ray is deviated through an angle of $$15^{\circ }$$ from its original direction. The refractive index of the medium is:

The combination of two identical cells, whether connected in series or parallel combination provides the same current through an external resistance of 2$$\Omega$$. The value of internal resistance of each cell is

Resistance of the wire is measured as 2 $$\Omega$$ and 3 $$\Omega$$ at 10$${}^{\circ }$$C and 30$${}^{\circ }$$C respectively. Temperature co-efficient of resistance of the material of the wire is :

A 72 $$\Omega$$ galvanometer is shunted by a resistance of 8 $$\Omega$$. The percentage of the total current which passes through the galvanometer is :

An aluminium wire is stretched to make its length, 0.4% larger. The percentage change in resistance is :

The equivalent resistance between points A and B in the given network is :

Two cells of same emf but different internal resistances r1 and r2 are connected in series with a resistance R. The value of resistance R, for which the potential difference across second cell is zero, is :

If n represents the actual number of deflections in a converted galvanometer of resistance G and shunt resistance S. Then the total current I when its figure of merit is K will be:

A teacher in his physics laboratory allotted an experiment to determine the resistance (G) of a galvanometer. Students took the observations for {1 \over 3} deflection in the galvanometer. Which of the below is true for measuring value of G?

What will be the most suitable combination of three resistors A = 2$$\Omega$$, B = 4$$\Omega$$, C = 6$$\Omega$$ so that \left( {{{22} \over 3}} \right)$$\Omega$$ is equivalent resistance of combination?

Two identical cells each of emf 1.5 V are connected in parallel across a parallel combination of two resistors each of resistance 20 $$\Omega$$. A voltmeter connected in the circuit measures 1.2 V. The internal resistance of each cell is :

An electric cable of copper has just one wire of radius 9 mm. Its resistance is 14 $$\Omega$$. If this single copper wire of the cable is replaced by seven identical well insulated copper wires each of radius 3 mm connected in parallel, then the new resistance of the combination will be :