Magnetic Effects of Electric Current — Science STD 10 — Question

A virtual, erect and magnified image of an object is to be produced with a concave mirror of focal length 12cm. Which of the following object distance should be chosen for this purpose?

When the switch S is closed in the figure given below, the pointer of the galvanometer moves to the right.

If S is kept closed, will the pointer:

1. Return to zero?
2. Stay over on the right?
3. Move to the left and stay there.
4. Move to and fro until S is opened.

A non-renewable source of energy is:

1. Wood.
2. Alcohol.
3. Hydrogen gas.
4. Natural gas.

Three students A, B and C focussed a distant building on a screen with the help of a concave mirror. To determine focal length of the concave mirror they measured the distances as given below:
Student A : From mirror to the screen.
Student B : From building to the screen.
Student C : From building to the mirror.
Who measured the focal length correctly:

When light rays enter the eye, most of the refraction occurs at the:

1. Crystalline lens.
2. Outer surface of the cornea.
3. Iris.
4. Pupil.

The magnification produced by a spherical mirror and a spherical lens is +0.8.

1. The mirror and lens are both convex.
2. The mirror and lens are both concave.
3. The mirror is concave but the lens is convex.
4. The mirror is convex but the lens is concave.

The human eye possesses the power of accommodation. This is the power to:

In order to obtain a magnification of −2 (minus 2) with a concave mirror, the object should be placed:

1. Between pole and focus.
2. Between focus and centre of curvature.
3. At the centre of curvature.
4. Beyond the centre of curvature.

Two resistors are connected in series gives an equivalent resistance of 10Ω. When connected in parallel, gives 2.4Ω. Then the individual resistance are:

Name the colour used in insulated wires of electrical appliance: