Question

Answer the following
1. What is the heating effect of electric current?
2. Write any three uses of electromagnets?
3. Explain the working of electric fuse.
4. State the characteristic of image formed by a plane mirror
5. What is rectilinear propagation of light?
6. Explain with the help of activity that seven colours of light can be
combined to produced white light.
7. Write the differences between
(a) Heat and temperature
(b) Clinical and lab thermometer​

Answer 1

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1) When electric current is supplied to a purely resistive conductor, the energy of electric current is dissipated entirely in the form of heat and as a result, resistor gets heated. The heating of resistor because of dissipation of electrical energy is commonly known as Heating Effect of Electric Current.

2) The electromagnetic spectrum covers a wide range of frequencies from cosmic rays to radio waves. The utility varies widely, for instance, gamma rays are used to destroy tumors, microwaves are used for heating, visible light helps us see, radio waves are used for radio channels .

3) An electric fuse is an electric device which interrupts the flow of current in an electric circuit. A fuse is usually a short piece of wire. The fuse is made up of a material which has high resistivity and low melting point, so that it melts down due to overheating of the wire during high current flow.

4)

• Plane mirror forms an erect image
• It forms a virtual image.
• Size of the image is same as that of the object.
• Image is formed at the same distance behind the mirror as the object stands in front of it.
• Image formed is a laterally inverted image i.e., right hand side of the object seems to be the left hand side and vice-versa.

5) Rectilinear propagation describes the tendency of Electromagnetic waves (light) to travel in a straight line. Light only deviates from a straight line when the medium it is travelling through changes density. This is called refraction.

6) The colors of white light splatted by a glass prism can be recombined to get white light by another identical glass prism. It can be done by putting an identical glass prism in the inverted position and allow all the colors of the spectrum to pass through the second prism.

7) Heat :

• The heat of an object is the total energy of all the molecular motion inside that object.
• It’s a measure of the number of atoms multiplied by the energy possessed by each atom.
• It is has the ability to do work

Temperature :

• Temperature is the measure of the thermal energy or average heat of the molecules in a substance.
• It is like a level which determines the direction in which the heat will flow. It is related to how fast the molecule within a substance are moving.
• It can be used to measure the degree of heat .

Clinical thermometer is meant for clinical purposes. It is developed for measuring the human body temperature. A Laboratory thermometer which is colloquially known as the lab thermometer, is used for measuring temperatures other than the human body temperature.

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