Q14 of 216 Page 478

i. Shruti draws magnetic field lines close to the axis of a current carrying circular loop. As she moves away from the centre of circular loop, she observes that the lines keep on diverging. Explain the reason for her observation.

ii. Write two properties of magnetic field lines.

(i) We know the magnetic field is stronger near the current carrying conductor and become weaker as we move from the conductor. In case of a current carrying circular loop, the magnetic field is stronger near the wire of circular loop and weaker at the centre of the loop. Due to this, the magnetic field lines appear as straight lines near the centre. And as we move towards the wire of circular loop . The magnetic field lines appear to be diverging so that they can be circular around the wire of the loop.


(ii) The properties of magnetic field lines are


(a) The direction of magnetic field lines is from North to South pole outside the bar magnet and North to South pole inside the magnet.


(b) Magnetic field lines never intersect each other.


More from this chapter

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12

A child while playing with his father’s spectacles burnt a hole in a piece of paper by focusing a small image of the sun on it.

i. What defect of vision his father is suffering from?


ii. Write two causes for this defect.


iii. Draw a ray diagram to show image formation by the defective eye.


iv. Draw a ray diagram showing corrected eye using proper lens.


OR


A person cannot see objects beyond 80 cm from his eye while a person with normal eyesight can see object easily placed up to 160 cm from the eye. Find the nature, the focal length and the power of the correcting lens.

 13

What is meant by overloading of an electrical circuit? Explain two possible causes due to which overloading may occur in the household circuit. Explain one precaution that should be taken to avoid the overloading of a domestic electric circuit.

 15

“We are looking for an alternative or non-conventional source of energy.” State three reason for it.

 16

i. Identify the acid and the base whose combination forms the common salt that you use in your food. Write the formula and chemical name of this salt. Name the source from where it is obtained.

ii. What is rock salt? Mention its colour and the reason due to which it has this colour.


iii. What happens when electricity is passed through brine? Write the chemical equation for it.


OR


i. Write the chemical name and chemical formula of washing soda.


ii. How is it obtained from sodium chloride? Give equations of the reactions.


iii. Why it is called a basic salt? Give its any one use.