NCERT Solutions for class 11 Physics | Chapter 2 - Units and Measurements

Questions
1 The density of the material of a cube is measured by measuring its mass and length of its side. If the maximum errors in the measurement of mass and the length are 3% and 2% respectively, the maximum error in the measurement of density is:
A 1%
B 5%
C 7%
D 9%

Answer:9%
2 The dimensional formula of kinetic energy is the same as that of:
A pressure
B work
C momentum
D force

Answer:work

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3 The kilowatt hour is a unit of:
A Energy
B electric charge
C Force
D electric power

Answer:Energy
4 The dimensions of h/e (h = Planck’s constant and e = electronic charge) are same as that of:
A magnetic flux
B electric flux
C electric field
D magnetic field

Answer:magnetic flux
5 The density of a cube is measured by measuring its mass and length of its sides. If the maximum errors in the measurement of its mass and length are 4% and 3% respectively, the maximum error in density is
A 1%
B 7%
C 5%
D 13%

Answer:13%
6 In a resonance tube with tuning fork of frequency 512 Hz, first resonance occurs at water level equal to 30.3 cm and second resonance occurs at 63.7cm. The maximum possible error in the speed is:
A 51.2 cm/sec.
B 102.4 cm/sec
C 204.8 cm/sec
D 153.6 cm/sec

Answer:204.8 cm/sec
7 A rectangular plate has length (2 0.02)cm ± and width (1 0.01)cm. ± The maximum percentage error in the measurement of its area is:
A 1%
B 2%
C 3%
D 5%

Answer:2%
8 If the units of length and force are increased four times, then the unit of energy will:
A Increase 8 times
B Increase 16 times
C Decreases 16 times
D Increase 4 times

Answer:Increase 16 times
9 If velocity, force and time are taken to be fundamental quantities find dimensions formula for
A KV–1FT–1
B KV–1FT
C KVF–1T–1
D KV–1F–1T

Answer:KV–1FT
10 The frequency of vibration f of a mass m suspended from a spring of spring constant k is given by relation of the type xy f=cmxky where c is a dimensionless constant. The values of x and y are:
A 1/2, 1/2
B –1/2, –1/2
C 1/2, –1/2
D –1/2, 1/2

Answer:–1/2, 1/2
11 Dimensional formula for latent heat is:
A M0L2T-2
B MLT-2
C ML2T-2
D ML2T-1

Answer:M0L2T-2
12 Which of the following sets cannot enter into the list of fundamental quantities in any system of units?
A length, mass, velocity
B length, time, velocity
C length, time, mass
D mass, time, velocity

Answer:length, time, velocity
13 Which of the following groups has different dimensions?
A Potential difference, emf, voltage
B Pressure, stress, Young’s modulus
C Heat, energy, work done
D Dipole moment, electric flux, electric field

Answer:Dipole moment, electric flux, electric field
14 In a particular system, the units of length, mass and time are chosen to be 10 cm, 10 g and 0.1 s respectively. The unit of force in this system will be :
A 0.1 N
B 1 N
C 10 N
D 100 N

Answer:0.1 N
15 The displacement of a particle is given by X=A Sin2kt where t denotes time. The unit of k is
A htz
B metre
C radian
D second

Answer:htz
16 Which of the following is not a unit of time
A solar year
B tropical year
C leap year
D light year

Answer:light year
17 The density of wood is 0.5 g cm-3 in cgs system of units. The corresponding value of SI units is
A 5000
B 500
C 5
D 0.5

Answer:500
18 The number of significant figures in 0.06900 is
A 5
B 4
C 2
D 3

Answer:4
19 The sum of the numbers 436.32, 227.2 and 0.301 in appropriate significant figures is
A 663.821
B 664
C 663.8
D 663.82

Answer:664
20 The mass and volume of a body are 4.237 g and 2.5 cm3, respectively. The density of the material of the body in correct significant figures is
A 1.6048 g cm-3
B 1.69 g cm-3
C 1.7 g cm-3
D 1.695 g cm-3

Answer:1.7 g cm-3

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