$A$ wire is bent in the shape of a right-angled triangle and is placed in front of a concave mirror of focal length $f$,as shown in the figure. Which of the figures shown in the four options qualitatively represent$(s)$ the shape of the image of the bent wire? (These figures are not to scale.)

The exposure time of a camera lens at the $f/2.8$ setting is $1/200$ second. The correct time of exposure at $f/5.6$ is......$sec$

An object is placed $60 \ cm$ in front of a convex mirror of focal length $30 \ cm$. $A$ plane mirror is now placed facing the object in between the object and the convex mirror such that it covers the lower half of the convex mirror. What should be the distance of the plane mirror from the object so that there will be no parallax between the images formed by the two mirrors (in $cm$)?

When sunlight falls normally on Earth,a luminous flux density (illuminance) of $1.57 \times 10^5 \; lm/m^2$ is produced on Earth. If the distance of Earth from the Sun is $1.5 \times 10^8 \; km$,what is the total luminous flux emitted by the Sun?

$A$ point source of light is $60\, cm$ from a screen and is kept at the focus of a concave mirror which reflects light on the screen. The focal length of the mirror is $20\, cm$. The ratio of average intensities of the illumination on the screen when the mirror is present and when the mirror is removed is: (in $: 1$)

If the focal length of the objective lens is increased,then: