8th Standard Science Chapter-6

Q11. The shape of the magnetic field lines produced by a current carrying conductor are:

Q12. An electric motor is a device which transforms

Q13. Which of the following diagrams correctly shows the magnetic field produced by a current- carrying wire?

Q14. The frequency of electricity produced by DC generator is equal to

Q15. A current flows in a wire running between the S and N poles of a magnet lying horizontally as shown in the figure below:

The force on the wire due to the magnet is directed:

Q11. The energy efficient device for producing light is:

Q12. The radiation present in the sunlight that gives us the feeling of hotness is

Q13. The major constituent of biogas is

Q14. The process by which energy is produced in the sun is

Q15. The diagram shows a simple calorimeter system for measuring the heat given out by a liquid fuel contained in the burner. The experimental data for four fuels A, B, C and D is given below. 100 ml (100g) of water was put in the calorimeter and a thermometer is used to measure the change in temperature. With the help of the data find the fuel which is the least efficient?