## Units and Measurement Questions and Answers Part-7

1. The unit of e.m.f . is
a) Joule
b) Joule-Coulomb
c) Volt–Coulomb
d) Joule/Coulomb

Explanation: Unit of e.m.f. = volt = joule/coulomb

2. Which of the following is not the unit of time
a) Micro second
b) Leap year
c) Lunar months
d) Parallactic second

Explanation: Parallactic second

3. Unit of self inductance is
a) $\frac{Newton-second}{Coulomb\times Ampere}$
b) $\frac{Joule/Coul omb\times Second}{Ampere}$
c) $\frac{Volt\times metre}{Coulomb}$
d) $\frac{Newton\times metre}{Ampere}$

Explanation: $\frac{Joule/Coul omb\times Second}{Ampere}$

4. To determine the Young's modulus of a wire, the formula is $Y=\frac{F}{A}\times\frac{L}{\triangle L}$   where L = length, A= area of cross-section of the wire, $\triangle L$   = change in length of the wire when stretched with a force F . The conversion factor to change it from CGS to MKS system is
a) 1
b) 10
c) 0.1
d) 0.01

Explanation:

5. Young's modulus of a material has the same units as
a) Pressure
b) Strain
c) Compressibility
d) Force

Explanation:

6. One yard in SI units is equal
a) 1.9144 metre
b) 0.9144 metre
c) 0.09144 kilometre
d) 1.0936 kilometre

Explanation: 1 yard = 36 inches = 36 * 2.54 cm = 0.9144 m

7. Which of the following is smallest unit
a) Millimetre
b) Angstrom
c) Fermi
d) Metre

Explanation: 1 fermi = 10-15 metre

8. Which one of the following pairs of quantities and their units is a proper match
a) Electric field –Coulomb /m
b) Magnetic flux – Weber
c) Power – Farad
d) Capacitance – Henry

Explanation: Magnetic flux – Weber

9. The units of modulus of rigidity are
a) $N-m$
b) $N\diagup m$
c) $N-m^{2}$
d) $N\diagup m^{2}$

Explanation: $N\diagup m^{2}$
b) $Fm^{-1}\left(Farad/meter\right)$
Explanation: $Fm^{-1}\left(Farad/meter\right)$