A student has to determine the focal length of a concave mirror by obtaining the image of a distant object on a screen. For getting best result he should focus—

A teacher gives a convex lens and a concave mirror of focal length of about $20 \mathrm{cm}$ each to his student and asks him to find their focal lengths by obtaining the image of a distant object. The student uses a distant tree as the object and obtains its sharp image, one by one, on a screen. The distance $d_1$ and $d_2$ between the mirror and the screen in the two cases and the nature of their respective sharp images are likely to be—

Parallel rays from a distant object incident on a convex lens forms an image on the screen. The diagram showing correctly the image of the object on the screen in figure is—

In an experiment to determine the focal length of a convex lens, a student obtained a sharp, inverted image of a distant tree on the screen behind the lens, she then removed the screen and looked through the lens in the direction of the object. She will see—

Given below are a few steps (not in proper sequence) followed in the determination of focal length of a given convex lens by obtaining a sharp image of a distant object—

$\left(A\right)$ Measure the distance between the lens and screen.

$\left(B\right)$ Adjust the position of the lens to form a sharp image.

$\left(C\right)$ Select a suitable distant object.

$\left(D\right)$ Hold the lens between the object and the screen with its faces parallel to the screen.

The correct sequence of steps for determination of focal length is—

A student has to determine the focal length of a convex lens by obtaining the image of a distant object on a screen. Which of the following measures should he take to obtain better results?

a) Select a lens of small diameter (say $3 \mathrm{cm}$).

 b) Select a lens of larger diameter (say $5 \mathrm{cm}$).

 c) Select an object very far from the lens.

 d) Select an object far, but not very far, from the lens.

 e) Keep all the lights of the room on.

 f) Keep minimum lights of the room on.

To find the focal length of a concave mirror, Sita should choose which one of the following set-ups?

To find the focal length of a concave mirror, Ram focuses a distant object with this mirror. The chosen object should be—

A student obtained a sharp inverted image of a distant tree on a screen placed in front of the concave mirror. Then he removed the screen and tried to look into the mirror. He would now see _____.