### Exercise 1

Question 21 :

Magnetism at the centre of a bar magnet is

A). minimum
B). maximum
C). zero
D). minimum or maximum
Answer : Option C

Question 22 :

It is more difficult to walk on a sandy road than on a concrete road because

A). sand is soft and concreter is hard
B). the friction between sand and feet is less than that between concrete and feet
C). the friction between sand and feet is more than that between concrete and feet
D). the sand is grainy but concrete is smooth
Answer : Option B

Question 23 :

Find the maximum velocity for the overturn of a car moving on a circular track of radius 100 m. The co-efficient of friction between the road and tyre is 0.2

A). 0.14 m/s
B). 140 m/s
C). 1.4 km/s
D). 14 m/s
Answer : Option D

Question 24 :

Of the following properties of a wave, the one that is independent of the other is its

A). amplitude
B). velocity
C). wavelength
D). frequency
Answer : Option A

Question 25 :

Lux is the SI unit of

A). intensity of illumination
B). luminous efficiency
C). luminous flux
D). luminous intensity
Answer : Option A

Explanation :

The SI unit of intensity of illumination (illuminance) is the lux. An illuminance of 1.0 lux is produced by 1.0 lumen of light shining on an area of 1.0 m^2.