The speed of a distant star is observed to be \(1\) light-year/century. This value, when expressed in SI, is (approximately):
1. \(3\times10^8~\text{m/s}\)    2. \(3\times10^6~\text{m/s}\)   
3. \(3\times10^4~\text{m/s}\) 4. \(300~\text{m/s}\)
Subtopic:  Measurement & Measuring Devices |
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Which of the following quantities have the same dimension?
(A) \(\dfrac{\text{(Magnetic flux)}^2}{\text{Electrical resistance}}\) (B) \(\text{Torque}\times\text{time}\)
(C) \(\text{Momentum}\times\text{length}\) (D) \(\dfrac{\text{Power}}{\text{time}}\)
1. B, C
2. A, B, C
3. B, D
4. A, B, C, D
Subtopic:  Dimensions |
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Which of the quantities below have the same dimensions?
(A) \(\dfrac{\text{electric field }\times\text{ magnetic field}}{\mu_0}\)
(B) \(\dfrac{\varepsilon_0\times\text{(electric potential)}^2\times\text{ velocity}}{\text{area}}\)
(C) \(\dfrac{\text{power}}{\text{area}}\)
1. A, B
2. B, C
3. A, C
4. A, B, C
Subtopic:  Dimensions |
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Which, of the following, is dimensionless?
1. \(\text{impedance}\times\text{conductance} \) 2. \(\dfrac{\text{emissive power}}{\text{emissivity}}\)
3. \(\dfrac{\text{electric field}}{\text{magnetic field}}\) 4. \(\dfrac{\text{inductance}}{\text{capacitance}}\)
Subtopic:  Dimensions |
 51%
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Darcy's law describes the volume flow rate \((Q)\) of a viscous fluid (viscosity : \(\mu\)) through a porous medium, under the action of a pressure difference. \(\frac{Q}{A}=\frac{k}{\mu}\left(\frac{{\large p}_{1}-{\large p}_{2}}{L}\right) \)
Here, \(k\) is the permeability of the medium. The unit of \(k\) is (SI units):

1. m
2. m2
3. m2/s
4. m/s2
Subtopic:  Dimensions |
 51%
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The quantity \(\eta\) is defined by:    \(\eta=\dfrac{1}{\mu_0\sigma}\)
where \(\mu_0\) is the permeability of free space and \(\sigma\) is the electrical conductivity (of a plasma). \(\eta\) is referred to as the magnetic diffusivity. Its SI unit is:
1. m2/s
2. m/s2
3. C-m2/s
4. T-m/s
Subtopic:  Dimensions |
 50%
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The quantities \(K,c,\eta\) represent the thermal conductivity, the specific heat capacity and the viscosity of a liquid. Which, of the following, is dimensionless?
1. \(Kc\eta\) 2. \(\Large\frac{Kc}{\eta}\)
3. \(\Large\frac{K\eta}{c}\) 4. \(\Large\frac{\eta c}{K}\)
Subtopic:  Dimensions |
 56%
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The diffusion equation is given by:
                         \(\dfrac{\partial n}{\partial t}=D\dfrac{\partial^2 n}{\partial x^2}\)
where \(n(x,t)\) is the concentration of particles per unit volume at position \(x\), at time \(t\). The dimensions of the diffusion constant \(D,\) are:
1. \(LT^{-1}\)
2. \(L^{-1}T\)
3. \(L^{5}T^{-1}\)
4. \(L^{2}T^{-1}\)
Subtopic:  Dimensions |
 56%
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What is the unit of the quantity represented by:    \(\dfrac{\text{(Angular momentum)}}{\text{(electric charge)}^2}\)

1. \(\Omega\) (ohm)
2. s/m
3. \(\text{H }\)(henry)
4. \(\text{F }\) (farad)
Subtopic:  Dimensions |
 59%
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The estimate of absolute error in the measurement of time using a clock is \(10^{-2}~\text{s}.\) The time difference, \(t=t_1-t_2,\) between two events is determined by using the clock. The error in \(t\) is:
1. \(10^{-2}~\text{s}\) 2. \(2\times10^{-2}~\text{s}\)
3. \({\Large\frac12}\times10^{-2}~\text{s}\) 4. zero
Subtopic:  Errors |
 60%
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