Questions

Distinguish Between.

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5 questions · self-marked practice — reveal the answer and mark yourself.

Question 13 Marks
Electric current and Potential difference
Answer
Electric current Potential difference
(i) The flow of electric charge per unit time is called electric current. (i) The difference in potential between the positive and negative terminal of a cell is the potential difference of that cell.
(ii) The S.I. unit of electric current is ampere. (ii) The S.I. unit of potential difference volt.
(iii) Ammeter is used to measure electric current. (iii) Voltmeter is used to measure electric current.
(iv) Current is represented by: $\mathrm{I}=\frac{\mathrm{Q}}{\mathrm{t}}$ (iv) Potential difference is represented by: $\mathrm{V}=\frac{\mathrm{W}}{\mathrm{Q}}$
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Question 23 Marks
Resistance in Series and Resistance in Parallel
Answer
Resistance in Series Resistance in Parallel
(i) Effective resistance of the resistors is equal to the sum of their individual resistances. (i) Inverse of the effective resistance is equal to the sum of the inverse of individual resistances.
(ii) The same current flows through each resistor. (ii) The total current flowing through the circuit is the sum of the currents flowing through individual resistors.
(iii) The effective resistance is larger than each of the individual resistances. (iii) The effective resistance of resistors connected in parallel is less than the least resistance of individual resistors.
(iv) This arrangement is used to increase the resistance in a circuit. (iv) This arrangement is used to decrease the resistance in a circuit.
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Question 33 Marks
Conductors and Insulators
Answer
Resistance Resistivity
(i) The hindrance to the flow of electrons is called resistance. (i) Resistivity is the specific property of the material of a conductor.
(ii) The S.I. unit of resistance is ohm (Q). (ii) The S.I. unit of resistivity is ohm-metre (Q – m).
(iii) It depends on temperature, area of cross-section, length of conductor and material of the conductor. (iii) It depends on material of the conductor.
(iv) Resistance can be changed as it depends of external factor as well. (iv) Resistivity cannot be changed as it depends of internal factors.
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Question 43 Marks
Ohmic conductors and Non-Ohmic conductors
Answer
Conductors Insulators
(i) Substances which have very low electrical resistances are called conductors. (i) Substances which have extremely high electrical resistances are called Insulators.
(ii) They contain a large number of free electrons. (ii) They contain practically no free electrons.
(iii) Conductors are mostly metals. (iii) Insulators are mostly non metals.
(iv) Conductor example iron, copper. (iv) Insulator example rubber, plastic.

Maharashtra Board Class 9 Science Solutions Chapter 3 Current Electricity

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Question 53 Marks
Voltmeter and Ammeter
Answer
Voltmeter Ammeter
(i) It is an instrument used to measure the potential difference between two terminals of a cell. (i) It is an instrument to measure the electric current flowing through a circuit.
(ii) It is connected in parallel with the cell. (ii) It is connected in series with the cell.
(iii) It has a very high resistance. (iii) It has a very low resistance.
(iv) Voltmeter has range of volts. (iv) Ammeter has range of amps.
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