Refraction through a Lens — Physics STD 10 — Question

Draw a neat labelled ray diagram to show the formation of image by a magnifying glass. State three characteristics of the image.

In a house there are 6 bulbs of 100 W each used for 4 hours a day, 4 bulbs of 60 W each used for 8 hours a day, an immersion heater of 2.5 kW used for 1 hour per day, and an electric iron of 800 W used for 2 hours per day. Calculate the cost of monthly electric bill for the month of April at the rate of 80 p per unit.

A refrigerator converts 100 g of water at 20°C to ice at -10°C in 73.5 minutes. Calculate the average rate of heat extraction from water in watt. (Sp. heat of ice= 2100 J/kgK, sp. heat of water = 4200 J/kgK, Sp. latent heat of ice = 336000 J/kg.)

State the snell’s laws of refraction of light.

State the class of levers and the relative positions of load (L) effort (E) and fulcrum (F) in a bottle opener?

A crowbar of length 100 cm is used to lift a load of 5 kgf. It has its fulcrum at a distance of 20 cm from the load. Calculate:
(i) the mechanical advantage of a crowbar and,
(ii) the effort applied at the other end.

The diagram below shows a rod lifting a stone.
(a) Mark position of fulcrum F and draw arrows to show the directions of load L and effort E.
(b) What class of lever is the rod?
(c) Give one more example of the same class of lever stated in part (b).

Distinguish between a real and a virtual image.

Explain the phenomenon of resonance giving examples.