Refraction of Refraction — Science STD 10 — Question

An electric circuit consisting of a 0.5m long nichrome wire XY, an ammeter, a voltmeter, four cells of 1.5V each and a plug key was set up.

1. Draw a diagram of this electric circuit to study the relation between the potential difference maintained between the points ‘X’ and ‘Y’ and the electric current flowing through XY.
2. Following graph was plotted between V and I values:

What would be the values of ratios when the potential difference is 0.8V, 1.2V and 1.6V respectively? What conclusion do you draw from these values?

3. What is the resistance of the wire?

Draw a diagram to show why distant objects cannot be seen distinctly by a myopic eye. List two reasons due to which this defect of vision may be caused. A person with a myopic eye
cannot see objects clearly beyond a distance of 2 m. Name the type of corrective lens that would be needed to correct the defect of vision and draw a ray diagram to show how the defect
gets corrected.

When a spherical mirror is held towards the sun and its sharp image is formed on a piece of a carbon paper for some time, a hole is burnt in the carbon paper.

1. What is the nature of spherical mirror?
2. Why is a hole burnt in the carbon paper?
3. At which point of the spherical mirror the carbon paper is placed?
4. What name is given to the distance between spherical mirror and carbon paper?
5. What is the advantage of using a carbon paper rather than a white paper?

State and explain the laws of reflection of light at a plane surface (like a plane mirror), with the help of a labelled ray-diagram. Mark the angles of ‘incidence’ and ‘reflection’ clearly on the diagram. If the angle of reflection is 47.5°, what will be the angle of incidence?

i. State laws of reflection of light.
ii. An object of height 5.0 cm is placed at 15 cm in front of a concave mirror of focal length 10 cm . At what distance from the mirror should a screen be placed, so that a focussed image is obtained on it? Find the height of the image.

i. A concave mirror of focal length 10 cm can produce a magnified real as well as virtual image of an object placed in front of it. Draw ray diagrams to justify this statement.
ii. An object is placed perpendicular to the principal axis of a convex mirror of focal length 10 cm . The distance of the object from the pole of the mirror is 10 cm . Find the position of the image formed.

Two lamps, one rated 40W at 220V and the other 60W at 220V, are connected in parallel to the electric supply at 220V.

1. 10 Draw a circuit diagram to show the connections.
2. Calculate the current drawn from the electric supply.
3. Calculate the total energy consumed by the two lamps together when they operate for one hour.

Differentiate between myopia and hypermetropia. What type of spectacles should be worn by a person having the defects of myopia as well as hypermetropia? How does it help?

An object is placed 15cm from (a) a converging mirror, and (b) a diverging mirror, of radius of curvature 20cm. Calculate the image position and magnification in each case.

Two lamps, one rated 40W at 220V and the other 60W at 220V, are connected in parallel to the electric supply at 220V.

1. 10 Draw a circuit diagram to show the connections.
2. Calculate the current drawn from the electric supply.
3. Calculate the total energy consumed by the two lamps together when they operate for one hour.