Light – Reflection and Refraction — Science STD 10 — Question

A person finds difficulty in seeing nearby objects clearly. His vision can be corrected by using spectacles containing:

A piece of wire of resistance R is drawn to double its length. The new resistance is.

If the current I through a resistor is increased by 100% (assume that temperature remains unchanged), the increase in power dissipated will be:

A ray of light travelling in air goes into water. The angle of refraction will be:

1. 90°
2. Smaller than the angle of incidence.
3. Equal to the angle of incidence.
4. Greater than the angle of incidence.

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.

Which of the following figures shows the correct magnetic field lines?

While performing the experiment to trace the path of a ray of light passing through a glass prism, four students marked the incident ray and the emergent ray in their diagrams in the manner shown below:

Study the following ray diagram:

In this diagram, the angle of incidence, the angle of emergence and the angle of deviation respectively have been represented by.

Linear magnification produced by a concave mirror may be:

1. Less than 1 or equal to 1.
2. More than 1 or equal than 1.
3. Less than 1, more than 1 or equal to 1.
4. Less than 1 or more than 1.

An electric kettle for use on a 230V supply is rated 3000W. For safe working, the cable connected to it should be able to carry at least: