Physics Questions and Answers – Capacitors and Capacitance

«
»

This set of Physics Multiple Choice Questions & Answers (MCQs) focuses on “Capacitors and Capacitance”.

1. What is the dimensional formula of capacitance of a capacitor?
a) M1L2T-4I-2
b) M-1L-2T4I2
c) M-1L-2T6
d) M-2L2T4
View Answer

Answer: b
Explanation: We know that Capacitance=Charge*(voltage)-1
Now charge=current*time=[I1T1].
voltage=electric field*distance, and electric field=force*(charge)-1
Since we know the dimensional formula of force is [M1L1T-2], therefore,
Electric field=[M1L1T-2] * [I1T1]-1=[M1L1T-3I-1].
Finally, voltage becomes=[M1L1T-3I-1] *L.
Hence, we conclude that dimensional formula of capacitance is [I1T1] * ([M1L1T-3I-1] *L)-1 that is M-1L-2T4I2.
advertisement

2. When ‘n’ capacitors are connected in series the total capacitance(C) of the combination is given by ______
a) C=C1+C2+C3+C4+…..+Cn
b) C=C1*C2*C3*C4*…..*Cn
c) \(\frac {1}{C} = \frac {1}{C_1} + \frac {1}{C_2} + \frac {1}{C_3} + ……. + \frac {1}{C_n}\)
d) C=\(\frac {(C_1+C_2+C_3+C_4+……+C_n)}{n}\)
View Answer

Answer: c
Explanation: The equivalent capacitance of the parallel plate capacitors connected in series is given by the sum of the reciprocals of the individual capacitances. That is mathematically,
\(\frac {1}{C} = \frac {1}{C_1} + \frac {1}{C_2} + \frac {1}{C_3} + ……. + \frac {1}{C_n}\)

3. What is the value of capacitance of a capacitor if it has a charge of 9C and voltage of 5V?
a) 1.8F
b) 45F
c) 4.5F
d) 8.1F
View Answer

Answer: a
Explanation: Since we know that capacitance=\(\frac {charge}{voltage}\).
Therefore capacitance=\(\frac {9}{5}\)=1.8F.
advertisement
advertisement

4. The total capacitance of capacitors connected in parallel is given by _____
a) product of the individual capacitors in parallel
b) sum of all the individual capacitors in parallel
c) sum of their reciprocals
d) product of their reciprocals
View Answer

Answer: b
Explanation: The equivalent capacitance of the capacitors connected in parallel is given by sum of their individual capacitances, that is if there are n capacitors in parallel the total capacitance is given by, C=C1+C2+C3+C4+…..+Cn.

5. What is the total charge on the parallel plate capacitor shown?

a) 2Q
b) \(\frac {Q}{2}\)
c) 0
d) \(\frac {-Q}{2}\)
View Answer

Answer: c
Explanation: Since the total charge on a capacitor is given by sum of the charges on the two parallel plates, here charge on each plate is equal and opposite, hence –Q+Q=0. Therefore, the total charge on the capacitor is 0.
advertisement

6. What happens to the capacitance when a dielectric material is inserted between the plates of a parallel plate capacitor?
a) Capacitance decreases
b) Capacitance remains same
c) Capacitance increases
d) Depends upon the material of the dielectric
View Answer

Answer: c
Explanation: When a dielectric material is inserted between the plates of the parallel plate capacitor, the capacitance of the capacitor increases with a factor of K. That is C=KC0.

Sanfoundry Global Education & Learning Series – Physics – Class 12.

advertisement

To practice all areas of Physics, here is complete set of 1000+ Multiple Choice Questions and Answers.

Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Join our social networks below and stay updated with latest contests, videos, internships and jobs!

advertisement
advertisement
Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter