A source of light is placed at a distance of 50cm from a photocell and the cutt-off potential is found to be `V_(0)`. If the distance between the light source and the photocell is made 25cm, what will be the new cutt-off potential? Justify your answer.

A screen is placed at a distance of 5 cm from a point source. A 5 mm thick piece of glass of refractive index 1.5 is placed between them. What is the length of optical path between the source and the screen ?

A point source of light is placed at the midpoint of two concave mirror (facing each other) of focal length f , What should be the magnitude of the distance of separation d between the two mirrors for a single image to be formed?

A monochromatic source of light is kept at a distance of 0.2 m from a photoelectric cell. Stopping potential V_(0) and saturation current I_(0) are 0.6 V and 18.0 mA, respectively. Now the source is kept at a distance of 0.6 m from the cell. Then

A body is kept at rest at a distance of 10 cm from the centre of a gramophone disc. If the coefficient of friction between the body and the disc is 0.3, then for what maximum rps of the disc, will the body not be thrown off the disc?

A point object is placed on the axis of a thin convex lens of focal length 0.05 m at a distance of 0.2 m from the lens and its image is formed on the axis. If the object is now made to oscillate along the axis with a small amplitude of A cm, then what is the amplitude of oscillation of the image ? [you many assume, 1/(1+x) = 1-x , where x lt lt 1 ]

The focal lengths of the two lenses of a compound microscope are 0.5 cm and 1 cm respectively . An object is placed at a distance of 1 cm from the objective. If the final image of the object is formed at a distance of 25 cm from the eye , what is the distance between the two lenses and the magnifying power of the microscope ?

In Young's double slit experiment the wavelenght of light used is 5000 Å the slit -separation is 0.2 mm and the screen is placed at a distance 200 cm from the slits . Central maxima is at x=0 . If the central maxima is assumed as the zeroth bright band then what will be the distance of the third bright band?

A parallel plate 300 mu F capacitor is charged to 200 V, and is then disconnected from the source. If the distance between its plates is halved, what will be the potential difference between the plates and the change in energy stored in it?