Class XI Physics-Units & Measurements

which of the following pairs of quantities has the same dimension?

• force & work done

• momentum & Impulse

• pressure & force

• surface tension & stress

[ML²T^-2] are the dimensions of

• force

• torque

• momentum

• power

If error in radius is 3 %, what is the error in volume of sphere?

• 3 %

• 27 %

• 9 %

• 6 %

Which of the following is a dimensionless quantity ?

• strain

• stress

• specific heat

• Quantity of Heat

SONAR emits which of the following waves ?

• Radio

• visible light

• ultra sound

• X- rays

Length can not be measured by

• fermi

• micron

• debye

• light year

If x = at + bt², where x is the distance in km while t is time in sec, then the unit of b is

• km/s

• kms

• km/s²

• kms²

If the dimensions of a physical quantity are given by M^aL^bT^c

, then the physical quantity will be

• velocity if a =1, b=0, c= -1

• acceleration if a = 1, b = 1, c= -2

• force if a = 0, b= -1, c= -2

• pressure if a = 1, b= -1, c= -2

The respective number of significant figures for the numbers 34.098, 0.008, 7.8 x 10^-3 are

• 5, 4, 2

• 5, 1,2

• 4, 4, 5

• 5, 3, 2

If the voltage across a bulb rated 220 V-100 W drops by 2.5 % of its rated value, the percentage of the rated value by which the power would decrease is

• 20 %

• 5 %

• 2.5 %

• 10 %