MCQGeeks
0 : 0 : 1
CBSE
JEE
NTSE
NEET
English
UK Quiz
Quiz
Driving Test
Practice
Games
NEET
Physics NEET MCQ
Units, Dimension And Measurement Mcq
Quiz 3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Q.1
A wire of length l = 6±0.06cm and radius r = 0.5±0.005 cm and mass m = 0.3±0.003 gm. Maximum percentage error is density is .. [ IIT 2004]
0%
a) 4
0%
b) 2
0%
c) 1
0%
d) 6.8
Explanation
We know that density = mass/ volume ρ = m / lπr2 Thus relative error Here l = 6 Δl = 0.06cm, r =0.5cm and Δr = 0.005cm m= 0.3gm and Δm = 0.003gm By substituting value in avbove equation we get Relative error as 0.004 Percentage error = Relative error × 100 = 4% Answer: (a)
Q.2
The physical quantities which do not have same dimensions are .... [AIEE 2003]
0%
a) torque and work
0%
b) momentum and plank's constant
0%
c) stress and young's modulus
0%
d) speed and (µoεo)-1/2
Explanation
Momentum = [MLT-1] Planck's constant = h= E/f = ML2T-2 / T-1 Plank's constant = ML2T-1 Answer: (b)
Q.3
A body of mass m=3.513 kg is moving along the x-axis with speed of 5.00 m/s. The magnitude of its momentum is recorded as .. [ AIEE - 2008]
0%
a) 17.6 kgms-1
0%
b) 17.565 kgms-1
0%
c) 17.56 kgms-1
0%
d) 17.57 kg ms-1
Explanation
Momentum p = mv p = (3.513)×(5.00) p = 17.6 Rounded off to get three significant figures Answer: (a)
Q.4
Dimension of 1 / (µo εo ) , where symbols have usual meanings, are .. [ AIEE 2003]
0%
a) L-1T
0%
b) L-2T2
0%
c) L2T-2
0%
d) LT-1
Explanation
We know that given formula is for square of velocity of light Thus option (c) is correct Answer:(c)
Q.5
In an experiment the angle are required to be measured using an instrument, 29 divisions of the main scale exactly coincide with the 30 divisions of the vernier scale. If the smallest division of the main scale is half a a degree (0.5°), then the least count of the instrument is .. [ AIEE 2009]
0%
a) half minute
0%
b) one degree
0%
c) half degree
0%
d) one minute
Explanation
30 Division of vernier scale coincide with 29 divisions of main scales Therefore 1V.S.D = 29/30 M.S.D Least count = 1M.S.D. - 1VSD Least Count = 1 M.S.D - 929/30) M.S.D. Least Count = (1/30)MSD Least Count = (1/30)×0.5° = 1 minute Answer: (d)
Q.6
Two full turns of the circular scale of a screw gauge covers a distance of 1mm on its main scale. the total number of divisions on the circular scale isFurther, it is found that the screw gauge has a zero error of -0.03mm. While measuring the diameter of a thin wire,a student notes the main scale reading of 3mm and the number of circular scale division in line with the main scale asThe diameter of the wire is .. [ AIEE 2008]
0%
a) 3.32 mm
0%
b) 3.73mm
0%
c) 3.67mm
0%
d) 3.38mm
Explanation
Least count of screw gauge = (0.5/50)mm = 0.01mm ∴ Reading = [ main scale reading + circular scale reading × L.C.] -(zero error) ∴ reading = [ 3.0+ 35×0.01] -(-0.03) = 3.38mm Answer: (d)
Q.7
The percentage error in measurement of mass and speed is 2% and 3% respectively. The error in kinetic energy obtained by measuring mass and speed will be.. [ CBSE-PMT 1995]
0%
a) 12%
0%
b) 10%
0%
c) 8%
0%
d) 2%
Explanation
Formula for K.E , E = ½ (mv2 Thus percentage error Answer: (c)
Q.8
The ratio of the dimension of Planck's constant and that of the moment of inertia is the dimension of .. [ CBSE-PMT 2005]
0%
a) time
0%
b) frequency
0%
c) angular momentum
0%
d) velocity
Explanation
As angular momentum mvr = nh/2π or Iω = nh/2π h = 2πIω /n Moment of inertia = I Answer:(b)
Q.9
The unit of the Stefan -Boltzmann constant is .. [ CBSE-PMT 2002]
0%
a) W/m2K4
0%
b) W/m2
0%
c) W/ m2K
0%
d) W/ m2K2
Explanation
E = σAT4 σ = E / AT4 σ = W/m2K4 Answer: (a)
Q.10
If the error in measurement of radius of sphere is 2% then the error in the determination of volume of the sphere will be .. [ CBSE-PMT 2008]
0%
a) 4%
0%
b) 6%
0%
c) 8%
0%
d) 2%
Explanation
Volme of Sphere V = (4/3)π r3 Percentage error in volume Thus error in volume = 3×2% = 6% Answer: (b)
Q.11
The dimensional formula of angular velocity is .. [ JIPMER 1993]
0%
a) M0L0T-1
0%
b) ML-1T-1
0%
c) M0L1T-1
0%
d) ML0T-2
Explanation
angular velocity ω = 2π / T Thus M0L0T-1 Answer: (a)
Q.12
A physical quantity is represented by S= MxL-yTz. if percentage error in the measurement of M,L,T are α%, β% and γ% respectively, then total percentage error is
0%
a) (αx+βy+γz)%
0%
b) (αx-βy+γz)%
0%
c) (αx+βy-γz)%
0%
d) none of above
Explanation
According to formula for % error Answer: (a)
Q.13
The result of adding 3.6×10-6 and 2.2×10-5 with due regard to significant figure is
0%
a) 38.2×10-5
0%
b) 2.6×10-5
0%
c) 3.8×10-6
0%
d) 2.6×10-6
Explanation
3.6×10-6 = 0.36×10-5 + 2.5 ×10-5 = 2.56×10-5 rounded to one place 2.6×10-5 Answer: (b)
Q.14
Which of the following is the correct pair of physical quantity with its unit?
0%
a) electric field - coulob/m
0%
b) magnetic flux - weber
0%
c) power - farad
0%
d) capacitance - henry
Explanation
Answer : (b)
Q.15
The time period of a soap bubble is T ∝ Pa dbSc, where P is pressure, d is density and S is surface tension, then the values of a,b,c are respectively:
0%
a) -1,-2,3
0%
b) -3/2, 1/2, 1
0%
c) 1, -2, -3/2
0%
d) 1, 2, 1/3
Explanation
Dimension of Pressure P =F/A= [ ML-1 T-2] Dimensions of density d =M/V= [ ML-3] Dimensions of surface tension S = F/L = [ML0T-2] Dimension of time is = [T] Writing dimensions on both side and comparing powers of M,L,T we get [M0L0T] = [ ML -1 T-2]a [ ML -3]b [ML 0T -2]c [M0L0T] = M a+b+c L -a-3b T -2a-2c Thus a+b+c = 0 --(1) -a-3b = 0 --(2) -2a-2c = 1 --(3) from equation (3) a+c = -1/2 --(4) equation (1) - (4) we get b = 1/2 substituting value of "b" from above in equation (2) a = -3/2 by substituting values of "a" and "b" in equation (1) we get a c = 1 thus a= -3/2, b= 1/2 c= 1 Answer:(b)
Q.16
The formula for the periodic time of a simple pendulum is T = 2π(l/g) 1/The fractional error in the measurement of the period T is ±x and that in the measurement of length'l' is ±y. The fractional error in the calculated value of g is not grater than..
0%
a) x+y
0%
b) x-y
0%
c) 2x+y
0%
d) 2x-y
Explanation
form given equation g = 4π2l / T2 fractional error Here (Δl/l) = ±y and (ΔT/T) = ±x ∴ maximum error = y+2x Answer: (c)
Q.17
The unit of electric field is not equivalent to .. [ Raj. PMT 1995]
0%
a) N/C
0%
b) J/C
0%
c) V/m
0%
d) J/Cm
Explanation
J/C is unit for work done per unit charge is for potential V . Thus J/C don't represent electric field. Answer: (b)
Q.18
A force F is given by F = at + btWhere t is time. What are the dimensions of a and b ? [ BHU 1998]
0%
a) MLT -3 and ML 2T 4
0%
b) MLT -3 and MLT -4
0%
c) ML2T-1 and ML2T -1
0%
d) ML 2T -2 and MLT -1
Explanation
Accoring to principle of homogeneity Every term on right side of equation should have the dimension of left side term F ∴ dimension of at should have the dimension of F aT = MLT-2 [a]=MLT-3 Dimension of bt2 should have dimension of F bT2 = MLT-2 b = MLT-4 Answer: (b)
Q.19
If L and R represent inductance and resistance respectively, then the dimension of L/R will be (MPPMT 1998]
0%
a) ML0T0
0%
b) M0L0T
0%
c) M0L0T-2
0%
d) M0LT-2
Explanation
Dimesion formula of Inductance L = [M1L2I-2T-2] Dimensions formula of resistance R=M1L2I-2T-3] ∴ L/R = T Answer:(b)
Q.20
The dimension formula for latent heat is .. [IIT 1992]
0%
a) M0L2T-2
0%
b) MLT-2
0%
c) ML2T-2
0%
d) ML2T-1
Explanation
latent heat is amount of energy required to change the state of one unit mass of substance Latent heat = Heat / mass latent heat dimensions = ML2T-2 / M Latent heat dimensional formula = M0L2T-2 Answer: (a)
Q.21
One second is defined equal to .. [MNR 1986]
0%
a) 1650763.73 periods of Krypton clock
0%
b) 652189.63 periodes of Krypton clock
0%
c) 1650765.73.73 periods of Caesium clock
0%
d) 9192631770 periods of Caesium clock
Explanation
Answer: (d)
Q.22
A spherical body of mass m and radius r is allowed to fall in a medium of viscosity η. the time in which the velocity of the body increases from zeroto 0.63 times the terminal velocity is called time constant (τDimensionally τ can be represented by: [ AIIMS 1987]
0%
a)
0%
b)
0%
c)
0%
d) none of the above
Explanation
since time constant is time τ should have dimensions of time In given options a,b,c don't have dimensions of time thus option (d) is correct Answer: (d)
Q.23
Poise are the units of
0%
a) Torque
0%
b) C.G.S unit of viscosity
0%
c) S.I. unitof surface tension
0%
d) Moment of inertia
Explanation
Answer:(b)
Q.24
The dimension of the ratio of an angular to linear momentum is [ MNR 1994]
0%
a) M0L1T0
0%
b) M1L1T1
0%
c) M1L2T-1
0%
d) M-1L-1T-1
Explanation
Angular momentum L = mvr Linear momentum P = mve L/P = r Thus ratio have the dimension of radius r = M0L1T0 Answer: (a)
Q.25
Dimension of calories are.. [CPMT 1985]
0%
a) ML2T-2
0%
b) MLT-2
0%
c) ML-2T-1
0%
d) ML2T-1
Explanation
Calories is unit of energy hence dimension formula of energy Answer: (a)
Q.26
A wire when heated shows a 2% increase in length the increase in cross-sectional area would be ... [ CPMT 1993]
0%
a) 1%
0%
b) 2%
0%
c) 4%
0%
d) 4π%
Explanation
A = πr2 Answer: (c)
Q.27
If unit of F and L increases 3 times, the unit of energy will decease: [ AFMC 1994]
0%
a) 3 times
0%
b) 6 times
0%
c) 9 times
0%
d) 27 times
Explanation
Energy = Force × displacement Now F and l increased 3 times Energy unit will decrease 9 times Answer:(c)
Q.28
The accuracy of ceasium clock is 1 part inWhat can be the maximum difference between two such clocks operating for about 3200 years(≈1011 s)
0%
a) Pratically no difference
0%
b) 1 second
0%
c) 1 minute
0%
d) 1 hour
Explanation
Given Δt / t = 1 / 1011, ∴ (Δt/t)× t = 1011 / 1011 = 1s Answer: (b)
Q.29
The dimensions of [JIPMER 1998]
0%
a) [A2L-3T4M-4]
0%
b) [A-2L-4T-4M]
0%
c) [A0L0T0M0]
0%
d) [AL-3T2M-1]
Explanation
Dimension of εo = [M-1L-3T4A2] Dimensions of e = AT Dimensions of h = M L2T-1 On substituting dimensions in equation we get option "c" Answer: (c)
Q.30
ML-1T-2 represents [ EAMCET 1995]
0%
a) Stress
0%
b) Young's modulus
0%
c) Pressure
0%
d) All of the above
Explanation
Stress = F/A Young's modulus = Stress / (Δl / l) Pressure = F/ A From above it is clear that all the options have same dimensional formula option (d) is correct Answer: (d)
0 h : 0 m : 1 s
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Report Question
×
What's an issue?
Question is wrong
Answer is wrong
Other Reason
Want to elaborate a bit more? (optional)
Support mcqgeeks.com by disabling your adblocker.
×
Please disable the adBlock and continue.
Thank you.
Reload page