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DPP - 01NCERT : Daily Practice Problems - PHYSICS - 27/09/2021 : Mandakini Study Institute - Patna
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## DPP - 01NCERT : Daily Practice Problems - PHYSICS - 27/09/2021

### DPP - 01NCERT : Daily Practice Problems - PHYSICS - 27/09/2021

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Q1. An oil drop of 12 excess electrons is held stationary under a constant electric field of 2.55 × 104
NC–1 (Millikan’s oil drop experiment). Thedensity of the oil is 1.26 g cm–3. Estimate the radius of the drop.
(g = 9.81 m s–2; e = 1.60 × 10–19 C).

Q2. A 12pF capacitor is connected to a 50V battery. How much electrostatic energy is stored in the capacitor?

Q3. A 600pF capacitor is charged by a 200V supply. It is then disconnected from the supply and is connected to another
uncharged 600 pF capacitor. How much electrostatic energy is lost in the process?

Q4. A long charged cylinder of linear charged density λ is surrounded by a hollow co-axial conducting cylinder. What is the electric field in the space between the two cylinders?

Q5. A charge of 8 mC is located at the origin. Calculate the work done in taking a small charge of –2 × 10–9 C from a point P (0, 0, 3 cm) to a point Q (0, 4 cm, 0), via a point R (0, 6 cm, 9 cm).

Q6. A storage battery of emf 8.0 V and internal resistance 0.5 Ω is being charged by a 120 V dc supply using a series resistor of 15.5 Ω. What is the terminal voltage of the battery during charging? What is the purpose of having a series resistor in the charging circuit?

Q7. In a potentiometer arrangement, a cell of emf 1.25 V gives a balance point at 35.0 cm length of the wire. If the cell is replaced by another cell and the balance point shifts to 63.0 cm, what is the emf of the second cell?

Q8. The number density of free electrons in a copper conductor estimated in Example 3.1 is 8.5 × 1028 m–3. How long does an electron take to drift from one end of a wire 3.0 m long to its other end? The area of cross-section of the wire is 2.0 × 10–6 m2 and it is carrying a current of 3.0 A.

Q9. A silver wire has a resistance of 2.1 Ω at 27.5 °C, and a resistance of 2.7 Ω at 100 °C. Determine the temperature coefficient of resistivity of silver.

Q10. The storage battery of a car has an emf of 12 V. If the internal resistance of the battery is 0.4 Ω, what is the maximum current that can be drawn from the battery?