Unit And Dimensions - NEET Physics Questions
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Unit And Dimensions

Question 51: easy

Plane angle and solid angle have:

[2022]

1. Both units and dimension
2. Units but no dimensions
3. Dimensions but no units
4. No units and no dimensions
View Answer

Plane angle (radian) and solid angle (steradian) are dimensionless quantities (ratios of lengths or areas) but possess units.

Question 52: easy

Dimensions of stress are:

[2020]

1. \(ML^2T^{-2}\)
2. \(ML^0T^{-2}\)
3. \(ML^{-1}T^{-2}\)
4. \(MLT^{-2}\)
View Answer

Stress is Force per unit Area. \([\text{Stress}] = [F]/[A] = (MLT^{-2})/L^2 = ML^{-1}T^{-2}\).

Question 53: easy

The dimension of Planck constant equals to that of:

[2001]

1. Energy
2. Momentum
3. Angular momentum
4. Power
View Answer

Planck's constant \(h\) has dimensions \(ML^2T^{-1}\). Angular momentum also has dimensions \(ML^2T^{-1}\).

Question 54: easy

Which of the following dimensions will be the same as that of time?

[1996]

1. \(L/R\)
2. \(C/L\)
3. \(LC\)
4. \(R/L\)
View Answer

The ratio \(L/R\) has the dimensions of time, \(T\).

Question 55: easy

Which of the following is a dimensional constant?

[1995]

1. Relative density
2. Gravitational constant
3. Refractive index
4. Poisson ratio
View Answer

A dimensional constant is a physical constant with dimensions. The Gravitational constant \(G\) is a dimensional constant with dimensions \(M^{-1}L^3T^{-2}\).

Question 56: easy

The dimensions of \(RC\) is:

[1995]

1. Square of time
2. Square of inverse time
3. Time
4. Inverse time
View Answer

The product \(RC\) represents the time constant of an \(RC\) circuit, and its dimension is time, \(T\).

Question 57: easy

Which of the following has the dimensions of pressure?

[1994,90]

1. \(MLT^{-2}\)
2. \(ML^{-1}T^{-2}\)
3. \(ML^{-2}T^{-2}\)
4. \(M^{-1}L^{-1}\)
View Answer

Pressure is defined as Force per unit Area. Its dimensions are \(MLT^{-2} / L^2 = ML^{-1}T^{-2}\).

Question 58: easy

Dimensional formula of self inductance is:

[1989]

1. \(MLT^{-2}A^{-2}\)
2. \(ML^2T^{-1}A^{-2}\)
3. \(ML^2T^{-2}A^{-2}\)
4. \(ML^2T^2A^{-1}\)
View Answer

The energy stored in an inductor is \(U = \frac{1}{2}LI^2\). Therefore, the dimensions of self-inductance \(L\) are \(U/I^2 = [ML^2T^{-2}]/[A^2] = [ML^2T^{-2}A^{-2}]\).

Question 59: easy

The dimensional formula of torque is:

[1989]

1. \(ML^2T^{-2}\)
2. \(MLT^{-2}\)
3. \(ML^{-1}T^{-2}\)
4. \(ML^{-2}T^{-2}\)
View Answer

Torque is calculated as Force \(\times\) perpendicular distance. So its dimensions are \([MLT^{-2}] \times [L] = [ML^2T^{-2}]\).

Question 60: easy

If \(C\) and \(R\) denote capacitance and resistance, the dimensional formula of \(CR\) is:

[1988]

1. \(M^0L^0T^1\)
2. \(M^0L^0T^0\)
3. \(M^0L^0T^{-1}\)
4. Not expressible in terms of MLT
View Answer

The product \(CR\) is the time constant of an RC circuit. Its dimension is time, \(T\), which can be written as \(M^0L^0T^1\).