Optics — Physics STD 12 — Question

The ozone layer absorbs radiation of wavelegnths

The condition for observing Fraunhofer diffraction from a single slit is that the light wavefront incident on the slit should be

Match the column – I and column – II:

Column I	Column - II
A) An object is placed at focus before a convex mirror	Magnification is -oo
B) An object is placed at centre of curvature before a concave mirror	Magnification is 0.5
C) An object is placed at focus before a concave mirror	Magnification is +1
D) An object is placed at centre of curvature before a convex mirror	Magnification is 0.33

a) (A) → (2); (B) → (3); (C) → (4); (D) → (1)
b) (A) → (2); (B) → (4); (C) → (3); (D) → (1)
c) (A) → (2); (B) → (4); (C) → (1); (D) → (3)
d) (A) → (3); (B) → (1); (C) → (2); (D) → (4)

Total electric fulx coming out of a unit positive charge put in air is

Two charges are placed in vacuum at a distance d apart. The force between them is F. If a medium of dielectric constant 2 is introduced between them, the force will now be

The energy in an electromagnetic wave is

In a step-down transformer, the input voltage is 22 kV and the output voltage is 550 V. The ratio of the number of turns in the secondary to that in the primary is-

Which of the following has maximum frequency?