NEET Physics Capacitors Grouping of Capacitors Energy Stored in a Capacitor and Van de Graff generator MCQs Set A

Question. On decreasing the distance between the plates of a parallel plate capacitor, its capacitance
(a) increases
(b) first increases then decreases
(c) decreases
(d) remains unaffected

Answer: A

Question. Energy is stored in a capacitor in the form of
(a) electrostatic energy
(b) light energy
(c) magnetic energy
(d) heat energy

Answer: A

Question. If in a parallel plate capacitor, which is connected to a battery,we fill dielectrics in whole space of its plates, then which of the following increases?
(a) Q and C
(b) E and C
(c)   V and E
(d) Q and V

Answer: A

Question.  When air in a capacitor is replaced by a medium of dielectric constant K, the capacity
(a) increases K times
(b) remains constant
(c) decreases K times
(d) increases K² times

Answer: A

Question. A conductor carries a certain charge. When it is connected to another uncharged conductor of finite capacity, then the energy of the combined system is
(a) less than that of the first conductor
(b) equal to that of the first conductor
(c) uncertain
(d) more than that of the first conductor

Answer: A

Question. Capacitiors are used in electrical circuits where applicances need more
(a) current
(b) power
(c) voltage
(d) resistance

Answer: A

Question. The work done in placing a charge of 8 × 10^–18 coulomb on a condenser of capacity 100 micro-farad is
(a) 32 × 10^–32 joule
(b) 3.1 × 10^–26 joule
(c) 4 × 10^–10 joule
(d) 16 × 10^–232 joule

Answer: A

Question. A sheet of aluminium foil of negligible thickness is introduced between the plates of a capacitor. The capacitance of the capacitor
(a) remains unchanged
(b) increases
(c) decreases
(d) becomes infinite

Answer: A

Question. The potential gradient at which the dielectric of a condenser just gets punctured is called
(a) dielectric strength
(b) dielectric number
(c) dielectric constant
(d) dielectric resistance

Answer: A

Question. In a charged capacitor, the energy resides
(a) in the field between the plates
(b) around the edges of the capacitor plates
(c) in both the positive and negative charges.
(d) in the positive charges

Answer: A

Question. Assertion : When a dielectric slab is gradually inserted between the plates of an isolated parallel-plate capacitor, the energy of the system decreases.
Reason : The force between the plates decreases
(a) Assertion is correct, reason is incorrect
(b) Assertion is incorrect, reason is correct
(c) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(d) Assertion is correct, reason is correct; reason is a correct explanation for assertion

Answer: A

Question. A parallel plate capacitor is charged by connecting it to a battery. Now the distance between the plates of the capacitor is increased. Which of the following remains constant ?
(a) Potential difference between the plates of capacitor
(b) Energy stored in the capacitor
(c) Charge on each plate of the capacitor
(d) Capacitance

Answer: A

Question. Two vertical metallic plates carrying equal and opposite charges are kept parallel to each other like a parallel plate capacitor. A small spherical metallic ball is suspended by a long insulated thread such that it hangs freely in the centre of the two metallic plates. The ball, which is uncharged, is taken slowly towards the positively charged plate and is made to touch that plate. Then the ball will
(a) oscillate between the two plates touching each plate in turn
(b) oscillate between the two plates without touch them
(c) come back to its original position and will remain there
(d) stick to the positively charged plate

Answer: A

Question. Eight drops of mercury of equal radii possessing equal charges combine to form a big drop. Then the capacitance of bigger drop compared to each individual small drop is
(a) 2 times
(b) 32 times
(c) 4 times
(d) 8 times

Answer: A

Question. Capacitance (in F) of a spherical conductor with radius 1 m is
(a) 1.1 × 10^–10
(b) 9 × 10^–9
(c) 10^–3
(d) 10⁶

Answer: A

Question. A parallel plate capacitor with air between the plates is charged to a potential difference of 500V and then insulated. A plastic plate is inserted between the plates filling the whole gap. The potential difference between the plates now becomes 75V. The dielectric constant of plastic is
(a) 4 × 10^–10 joule
(b) 16 × 10^–32 joule
(c) 3.1 × 10^–26 joule
(d) 32 × 10^–32 joule

Answer: A

Question. Three condensor each of capacitance 2F are put in series. The resultant capacitance is
(a) 2/3 F
(b) 5 F
(c) 3/2 F
(d) 6F

Answer: A

Question.  A parallel plate capacitor with air between the plates is charged to a potential difference of 500V and then insulated. A plastic plate is inserted between the plates filling the whole gap. The potential difference between the plates now becomes 75V. The dielectric constant of plastic is
(a) 20/3
(b) 10
(c) 5
(d) 10/3

Answer: A

Question. From a supply of identical capacitors rated 8 mF, 250V, the minimum number of capacitors required to form a composite 16 mF, 1000V is 
(a) 32
(b) 16
(c) 4
(d) 2

Answer: A

Question. A parallel plate air capacitor of capacitance C is connected to a cell of emf V and then disconnected from it. A dielectric slab of dielectric constant K, which can just fill the air gap of the capacitor, is now inserted in it. Which of the following is incorrect?
(a) The charge on the capacitor is not conserved
(b) The potential difference between the plates decreases K times
(c) The energy stored in the capacitor decreases K times
(d) None of these

Answer: A

Question. Van de Graaff generator is used to
(a) build up high voltage of few million volts
(b) store electrical energy
(c) decelerate charged particle like electrons
(d) None of these

Answer: A

Question. Which of the following is / are true about the principle of Van de Graaff generator?
(a) Both
(b) The action of sharp points
(c) The charge given to a hollow conductor is tranferred to outer surface and is distributed uniformly over it
(d)   None of these

Answer: A