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Electricity Revision Worksheet: Current, Voltage, and Resistance, Exercises of Physics

Physics

A revision worksheet covering various topics related to electric current, voltage, and resistance. It includes questions on current density, electric fields, resistance changes, specific resistance, mobility of charge carriers, power dissipation, resistivity, electrical conductivity, and more. Students are expected to identify regions of negative resistance and ohm's law obedience in a graph, understand the effect of heating on drift velocity, and calculate the ratio of resistances for two conductors.

Typology: Exercises

2020/2021

Uploaded on 09/11/2021

kanishka-aswani
kanishka-aswani 🇦🇪

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REVISION WORKSHEET – CURRENT ELECTRICITY
1.
Is current density a scalar or a vector quantity?
2.
A steady current is flowing in a cylindrical conductor. Does electric field exist with in
the conductor?
3.
When a straight wire of resistance R is bent into U-shape, does its resistance change?
4.
If the radius of a copper wire is doubled, will its specific resistance increase, decrease
or remain same?
5.
Plot a graph showing the variation of current versus voltage for a material GaAs.
Identify the region of
(i) negative resistance
(ii) where ohm’s law is obeyed.
6.
What is the effect of heating of a conductor on the drift velocity of free electron?
7.
Define the term Mobility of charge carriers in a conductor. Write its S.I unit.
8.
The V-I graph for two ohmic conductors are as shown in the figure. What us the ratio
of resistances of conductor 1 and conductor 2 in terms of θ1 and θ2?
9.
What happens to the power dissipation if the value of electric current passing
through a conductor of constant resistance is doubled?
10.
(i) Define the term resistivity and write the SI unit .
(ii) Define electrical conductivity of a conductor and give its SI unit.
11.
The metallic conductor bis at temperature θ1. The temperature of metallic conductor
is increased to θ2. How will the product of its resistivity and conductivity change?
12.
The emf of a cell is always greater than its terminal voltage. Why? Give reason
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Download Electricity Revision Worksheet: Current, Voltage, and Resistance and more Exercises Physics in PDF only on Docsity!

REVISION WORKSHEET – CURRENT ELECTRICITY

  1. Is current density a scalar or a vector quantity?
  2. A steady current is flowing in a cylindrical conductor. Does electric field exist with in the conductor?
  3. When a straight wire of resistance R is bent into U-shape, does its resistance change?
  4. If the radius of a copper wire is doubled, will its specific resistance increase, decrease or remain same?
  5. Plot a graph showing the variation of current versus voltage for a material GaAs. Identify the region of (i) negative resistance (ii) where ohm’s law is obeyed.
  6. What is the effect of heating of a conductor on the drift velocity of free electron?
  7. Define the term Mobility of charge carriers in a conductor. Write its S.I unit.
  8. The V-I graph for two ohmic conductors are as shown in the figure. What us the ratio of resistances of conductor 1 and conductor 2 in terms of θ 1 and θ 2?
  9. What happens to the power dissipation if the value of electric current passing through a conductor of constant resistance is doubled?
  10. (i) Define the term resistivity and write the SI unit. (ii) Define electrical conductivity of a conductor and give its SI unit.
  11. The metallic conductor bis at temperature θ 1. The temperature of metallic conductor is increased to θ 2. How will the product of its resistivity and conductivity change?
  12. The emf of a cell is always greater than its terminal voltage. Why? Give reason
  1. The potential difference applied across a given resistance is altered so that heat produced per second increases by a factor of 16. By what factor does the applied Potential difference change?
  2. Two electric bulbs whose resistances are in the ratio 1:2 are connected in parallel to a source of constant voltage. What will be the ratio of power dissipation in these wires?
  3. Two 120V light bulbs, one of 25W and the other of 200W were connected in series across a 240V line. One bulb burnt out almost instantaneously. Which one was burnt and why?
  4. Two heating coils, one of fine wire and other of thick wire, made of the same material and of the same length are connected one by one to a source of electricity. Which coil will produce heat at greater rate?
  5. Show variation of resistivity of Si with temperature in a graph.
  6. Two materials Si and Cu are cooled from 300K to 60K. What will be the effect on their resistivity?
  7. Define the current sensitivity of a galvanometer. Write its SI unit.
  8. The amount of electric charge passing through a cross-section of wire in time t is Q = At^2 + Bt + C Where A, B and C are constants having values 5,4 and 1 respectively.
  9. A cell of emf ‘E’ and internal resistance ‘r’ draws a current ‘I’. Write the relation between terminal voltage ‘V’ in terms of E,I and r.
  10. Two identical cells, each of emf E, having negligible internal resistance, are connected in parallel with each other across an external resistance R. What is the current through this resistance?
  11. A resistance R is connected across a cell of emf E and internal resistance r. A potentiometer measures the potential difference between the terminal of the cell as V. Write the expression for r in terms of E, V and R.
  12. On increasing the current drawn from a cell, the net potential difference across its terminals lowered, why?
  13. Is it possible that the terminal potential difference across the cell be zero? If yes, state the condition.
  14. State the condition under which the terminal potential difference across a battery and its emf are equal.
  1. State Kirchhoff’s rules of current distribution in an electrical network.
  2. In a Wheatstone’s bridge experiment, a student by mistake, connect key(K) in place of galvanometer (G) in place of Key (K). How will be the test for the balance of the bridge?
  3. The given circuit represents a balanced Wheatstone’s bridge. Calculate the value of resistance x.
  4. Why is Wheatstone bridge (Meter Bridge) method not suitable for measurement of very low and very high resistances?
  5. Derive an expression for drift velocity of free electrons in a conductor in terms of relaxation time.
  6. Establish a relation between electric current and drift velocity.
  7. Deduce Ohm’s law using concept of drift velocity. OR Obtain the expression for the current density in terms of relaxation time. OR Deduce the expression for the electrical resistivity of a conductor in terms of number density of free electrons and relaxation time.
  8. Draw a circuit diagram showing balancing of Wheatstone bridge. Use Kirchhoff’s rules to obtain the balance condition in terms of the resistances of four arms of Wheatstone bridge.
  9. Explain with the help of a circuit diagram how the value of (i) unknown resistance (ii) specific resistance of wire (iii) Combination of resistance (series and parallel) Can be determined using a Wheat stone bridge. Give the formula used. 49 (i) State the principle of working of a potentiometer. (ii) Explain with the help of a circuit diagram how to (a) Compare the emf of two primary cells

(b) Determine the internal resistance of given cell. (iii) How can the sensitivity of a potentiometer be increased? (iv) Write two possible causes for one sided deflection in the potentiometer experiment.

  1. (i) What is internal resistance of a cell? On What factors does it depend? (ii) Define terminal potential difference of a cell. Derive a relation between the internal resistance, emf and terminal potential difference of a cell. (iii)Two cells of different emfs and internal resistance are connected in series. Deduce the expression for (a) Equivalent emf (b) Equivalent internal resistance of the combination. (c) Condition for maximum current. (iv)Derive the condition for obtaining maximum current through an external resistance connected across a mixed grouping of cells.