For reading small letters with a lens:
Explanation:
A concave lens always produces virtual, erect and diminished images and the decrease in the size of the image depends on the position of the object.
Concave lens will shrink the size of the already small letters.
A convex lens produces real and virtual, erect and inverted, diminished, same sized and magnified image of the object, depending upon the position of the object on the principal axis.
When the object is placed between F and 2F of convex lens, an enlarged but inverted image of the object is formed. The magnified image makes it easier to read small letters but the inverted image is undesirable.
When the object is placed at a distance less than the focal length of convex lens, an enlarged and erect image of the object is formed, which makes it easier to read small letters.
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
The earth's magnetic field at a certain place has a horizontal component 0.3 Gauss and the total strength 0.5 Gauss. The angle of dip is
(a) 
|
(b) 
|
(c) 
|
(d) 
|
Assertion : The earth’s magnetic field is due to iron present in its core.
Reason : At a high temperature magnet losses its magnetic property or magnetism.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If assertion is false but reason is true. |
An ammeter whose resistance is 180 Ω gives full scale deflection when current is 2 mA. The shunt required to convert it into an ammeter reading 20 mA (in ohms) is
|
(a) 18 |
(b) 20 |
(c) 0.1 |
(d) 10 |
If rotational velocity of a dynamo armature is doubled, then induced e.m.f. will become
|
(a) Half |
(b) Two times |
(c) Four times |
(d) Unchanged |