A potential difference of V volt is applied across a copper wire of length I and diameter d. How will the drift velocity be affected if

(i) V is double    (ii) I is doubled.

In the diagram given below (figure), find the current drawn from the battery: 

(i) just when the switch S is closed.

(ii) when sufficient time has elapsed after closing the switch.

Microwaves, X-rays, U.V. rays, infrared rays.

Which of the above electromagnetic waves has—

(i) the shortest wavelength.

(ii) the lowest frequency.

29. In a Youngs double slit experiment with monochromatic light, fringes are obtained on a screen placed at a distance D from the slits. If the screen is moved by 5 x 10^-2 m towards the slits, the change in the fringe width is 3 x 10^-5 m If the distance between the slits is 10^-3m, calculate the wavelength of the light used. 

In a single slit diffraction pattern how does the angular width of central maximum change, when  

(i) the slit width is increased.

(ii) light of smaller wavelength is used.