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 wave travelling in air along x-direction is given by $${E_y} = 540\sin \pi \times {10^4}(x - ct)\,V{m^{ - 1}}$$. Then, the peak value of magnetic field of wave will be (Given c = 3 $$\times$$ 10⁸ ms^$$-$$1)

When you walk through a metal detector carrying a metal object in your pocket, it raises an alarm. This phenomenon works on :

An electron with energy 0.1 keV moves at right angle to the earth's magnetic field of 1 $$\times$$ 10^$$-$$4 Wbm^$$-$$2. The frequency of revolution of the electron will be :

(Take mass of electron = 9.0 $$\times$$ 10^$$-$$31 kg)