6. The following table is prepared for comparing the properties of resistances in different combinations. Rearrange the contents in each column to match them properly.
7. Write any two methods to provide first aid in the case of electric shock.
Answer
Give artificial respiration.
Raise the temperature of the body. Massage the muscles and bring them to the original condition.
Start first aid for the functioning of the heart by apply pressure on the check.
8. A conductor AB is placed in a magnetic field as shown in the figure.
(a)If you are moving the conductor outwards, then what will be the direction of current in the conductor ?
(b)If an electric current passes from A to B, then in which direction the conductor will move ?
[Inwards the magnet/Outwards the magnet]
Answer
a) B to A.
b) Outwards the magnet.
9. Observe the figure of a DC motor.
(a) Write the name of the parts labelled as A and B.
(b) What are the changes to be made so as to convert this device into an AC generator ?
Answer
a) A - Armature coil B - Split ring
b) Change Split ring by Slip ring
10. Write the reason for the twinkling of stars in the sky.
Answer
The twinkling of stars is due to atmospheric refraction. Atmosphere is made of several layers and the refractive indices keep on changing continuously due to this path of light rays from the star keeps on changing their path continuously. As a result the light entering the pupil of the eye goes on changing with time and stars appears twinkling. In short the ray of light appears to come from different points on reaching the eye after refraction.
Answer
7. Write any two methods to provide first aid in the case of electric shock.
Answer
Give artificial respiration.
Raise the temperature of the body. Massage the muscles and bring them to the original condition.
Start first aid for the functioning of the heart by apply pressure on the check.
8. A conductor AB is placed in a magnetic field as shown in the figure.
(a)If you are moving the conductor outwards, then what will be the direction of current in the conductor ?
(b)If an electric current passes from A to B, then in which direction the conductor will move ?
[Inwards the magnet/Outwards the magnet]
Answer
a) B to A.
b) Outwards the magnet.
9. Observe the figure of a DC motor.
(a) Write the name of the parts labelled as A and B.
(b) What are the changes to be made so as to convert this device into an AC generator ?
Answer
a) A - Armature coil B - Split ring
b) Change Split ring by Slip ring
10. Write the reason for the twinkling of stars in the sky.
Answer
The twinkling of stars is due to atmospheric refraction. Atmosphere is made of several layers and the refractive indices keep on changing continuously due to this path of light rays from the star keeps on changing their path continuously. As a result the light entering the pupil of the eye goes on changing with time and stars appears twinkling. In short the ray of light appears to come from different points on reaching the eye after refraction.
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