A student obtains a blurred image of an object on a screen by using a convex lens. In order to obtain a sharp image of the same object on the screen, he will have to shift the lens:

A student performs an experiment on finding the focal length of a convex lens by keeping a lighted candle on one end of laboratory table, a screen on its other end and the lens between them as shown in figure.

The positions of the three are adjusted to get a sharp image of the candle flame on the screen.

If now the candle flame were to be replaced by a distant lamp on a far away electric pole, the student would be able to get a sharp image of this distant lamp on the screen by moving—

Mohan, Sohan and Rahul separately measured the focal length of the same convex lens using the same distant tree as object. All of them measured the distance between the lens and the inverted image of the tree on the screen. Mohan obtained a sharp image on the screen and labelled the measured distance as ${\mathrm{f}}_1$

Sohan obtained a slightly smaller and somewhat blurred image on the screen. He labelled the measured distance as ${\mathrm{f}}_2$

Rahul obtained a slightly magnified and blurred image on the screen. He labelled the measured distance as ${\mathrm{f}}_3$.

The three measured values of focal length are likely to be related as—

To determine the focal length of a convex lens by obtaining a sharp image of a distant object, the following steps were suggested which are not in proper sequence —

$\left(\mathrm{I}\right)$ Hold the lens between the object and the screen.

$\left(\mathrm{II}\right)$ Adjust the position of the lens to form a sharp image.

$\left(\mathrm{III}\right)$ Select a suitable distant object.

$\left(\mathrm{IV}\right)$ Measure the distance between the lens and the screen.

The correct sequence of steps to determine the focal length of the lens is 

Mohan obtained a sharp inverted image of a distant tree on the screen placed behind the lens. He then moved the screen and tried to look through the lens in the direction of the object. He would see___

By using a convex lens, a student obtained a sharp image of his class-room window grill on a screen. In which direction should he move the lens to focus a distant tree instead of the grill?

A student focussed the image of a distant object using a device X on a white screen X as shown in the figure. If the distance of the screen from the device is $30 \mathrm{cm}$, select the correct statement about the device X.

A student obtained a sharp image of a burning candle, placed at the farther end of a laboratory table, on a screen using a concave mirror. For getting better value of focal length of the mirror, the subject teacher suggested him for focussing a well illuminated distant object. What should the student do?