Human Eye and Colourful World — Science STD 10 — Question

Which one of the following statements is not true?

The part of human eye which is sensitive to red, blue and green light is:

In an electrical circuit two resistors of 2Ω and 4Ω respectively are connected in series to a 6V battery. The heat dissipated by the 4Ω resistor in 5s will be:

1. 5J.
2. 10J.
3. 20J.
4. 30J.

The current passing through an electric kettle has been doubled. The heat produced will become:

1. Half.
2. Double.
3. Four time.
4. One-fourth.

In order to determine focal length of a concave mirror by obtaining the image of distant object on screen, you need to measure the distance between:

A student obtained a sharp image of the grills of a window on a screen using a concave mirror. His teacher remarked that for getting better results a well lit distant object (preferably the sun) should be focussed on the screen. What should be done for this purpose?

A car headlight bulb working on a 12V car battery draws a current of 0.5A. The resistance of the light bulb is:

An MCB which cuts off the electricity supply in case of short-circuiting or overloading works in the:

1. Chemical effect of current.
2. Heating effect of current.
3. Magnetic effect of current.
4. Electroplating effect of current.

For a ray of light passing through a glass slab.

The lateral displacement was correctly measured as:

A convex lens has a focal length of 10cm. At which of the following position should an object be placed so that this convex lens may act as a magnifying glass?