Short Answer TypeName any two electromagnetic waves, which have a frequency higher than that of violet light. State one uses of each.
i) X-rays: They are used as diagnostic tool in medicine and as a treatment for certain types of cancer.
ii) UV rays: They are used to detect counterfeit currency.
State the energy change which takes place when a magnet is moved inside a coil having a galvanometer at its ends. Name this phenomenon.
The energy changes that takes place are mechanical into magnetic into electrical.
This phenomenon is called electromagnetic induction.
Why does the temperature of the surroundings start falling when the ice of a frozen lake starts melting?
Ice has the highest specific latent heat of fusion of 333,000 Jkg-1. Thus, when the ice is in a frozen state lake starts melting as it absorbs large amount of heat energy from the surroundings. This leads to a decrease in the atmospheric temperature.
State two ways by which the frequency of the transverse vibrations of a stretched string can be decreased.
Two ways by which the frequency of the transverse vibrations of a stretched string can be decreased:
i) By increasing the length of the string.
ii) By decreasing the tension in the string.
How many alpha and beta particles are emitted when uranium nucleus 
Alpha particles = 8, beta particles = 6
Four resistances of 2 ohm each are joined end to end to form a square ABCD. Calculate the equivalent resistance of the combination between any two adjacent corners.
Resistors, R1, R2 and R3 are ins eries, therefore their equivalent resistance is
RS = R1 + R2 + R3 = 2 + 2 + 2 = 6 ohm
Now, RS and R4are in parallel, therefore equivalent resistance of the combination between two adjacent corners is, 
With the help of an equation, state the mechanism of energy production in a nuclear fusion reaction.
In a nuclear fusion reaction a deuteron combines with a deuteron to form helium with the release of tremendous amount of energy. This combination takes place at a high temperature in accordance with the equation,
Calculate the heat energy that will be released when 5.0 kg of steam at 100oC condenses to form water at 100o C. Express your answer in S.I. unit. (Specific latent heat of vaporization of steam is 2268 kJ.kg)
Mass of steam, m = 5 g = 5 x 10-3 kg
Temperature of steam = 100oC
Specific latent heat of vaporization of steam, L = 2268 kJkg-1
Heat energy required, Q = mL
= 5 x 10-3 x 2268 x 103
= 1.134 x 104 J
In a three-pin plug, why is the earth pin made longer and thicker than the other two pins?
The earth pin is made longer and thicker,
i) so that the earth connection is made first,
ii) it is made thick so that its resistance is low and any leakage of current flows easily into the earth.
Draw a labeled diagram of an A.C. generator.
The labeled diagram of an a.c. generator is given below:
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