Question Library

An immersion heater is rated 1500W. How long does it take the heater to raise the temperature of 1 kg of water by 30°C? (Assume heat lost to the surrounding is negligible, Specific heat capacity of water 4200Jkg-1K-1)

The equation PxVyTz = Constant is Charles’ law if

Arrange the following in the order of their increasing frequency. I. Visible light II. Gamma rays III. Radio waves IV. Infra-red radiation V. Ultra-violet radiation

a) Define diffusion. (b) State two applications of electrical conduction through gases.

You are provided with a measuring cylinder, two different tins labeled C and D, a thermometer, and other necessary materials. Use the measuring cylinder provided to measure 100 cm of water and pour it into the tin label. Heat the water in the tin almost to boiling (90^\circC). Remove the tin and place it on a cork or wooden stand. Insert the thermometer into the tin and record the temperature of the water every minute starting from 85^\circC until the temperature falls to 60^\circC. Repeat the experiment with the tin labeled D using exactly the same volume of water and temperature range. Tabulate your readings. On the same graph sheet and using the same axis and scales, plot two graphs of temperature on the vertical axis and time on the horizontal axis from the readings obtained using tins C and D. Label the graphs appropriately as C and D to correspond with the tins used. From each graph, read off the time taken to cool from 85^\circC to 65^\circC. State two precautions taken to ensure accurate results. (b)i. Explain how heat losses by radiation and convection are minimized in a vacuum flask. ii. State four factors that affect the rate of evaporation of a liquid in an open container.

Water of mass 1.5kg is heated from from 30oC to 80oC using an electric kettle which is rated 5A, 230V. Calculate the time taken to reach the final destination [specific heat capacity of water 4200Jkg-1K-1]

A clinical thermometer is different from other mercury in glass thermometers owing to

I. Use a liquid with a high melting point. II. use a liquid of high volume expansivity. III. use a capillary tube of large diameter. which of the above best describes how the sensitivity of a liquid-in-glass thermometer can be enhanced?

The ratio of the coefficient of linear expansion of two metals \(\frac{∝_1}{∝_2}\) is 3:4. If, when heated through the same temperature change, the ratio of the increase in length of the two metals, \(\frac{e_1}{e_2}\) is 1:2, the ratio of the original lengths \(\frac{l_1}{l_2}\) is

The ice and steam point on a mercury-in-glass thermometer are 10cm and 30cm respectively. Calculate the temperature in decree Celsius when the mercury meniscus is the 14cm mark

Which of the following statements distinguishes thermal conduction for convection? i. Conduction requires a material medium while convection does not ii. In convection, there is actual motion of hot material, while in conduction, molecules molecules vibrates faster about their mean positions iii. Conduction takes place in solids while convection takes place in fluids.

A cube made of metal of linear expansivity \(\alpha\) is heated through a temperature \(\theta\). If the initial volume of the cube is Vo, the correct expression for the increase in volume of the cube is

A body of mass 200g and specific heat capacity 0.4Jg-1k-1 cools from 37oC to 31oC. Calculate the quantity of the heat released by the body.

Which of the following factors can affect the speed of sound in air? i. The temperature of the surrounding ii. The direction of the wind iii. The pitch of the sound.

(a) Explain thermiopic emission (b) State two applications of electrical conduction through gases.