Magnetic Effects of Electric Current — Science STD 10 — Question

To convert an AC generator into DC generator:

The lamps in a house hold circuit are connected in parallel because:

A circular loop placed in a plane perpendicular to the plane of paper carries a current when the key is ON. The current as seen from points A and B (in the plane of paper and on the axis of the coil) is anti-clockwise and clockwise respectively. The magnetic field lines point from B to A. The N-pole of the resultant magnet is on the face close to:

In an electric motor, the direction of current in the coil changes once in each:

The coloured light having the maximum speed in glass prism is:

1. Blue.
2. Green.
3. Violet.
4. Yellow.

Which of the following statement is correct:

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.

The direction of current in the coil at one end of an electromagnet is clockwise. This end of the electromagnet will be:

1. North pole.
2. East pole.
3. South pole.
4. West pole.

Refractive index of diamond with respect to glass is 1.6. If the absolute refractive index of glass is 1.5, then the absolute refractive index of diamond is:

Study the following diagram and select the correct statement about the device 'X':