What is the meaning of the statement “The potential difference between two points is 1 V ” ? Name the device used to measure potential difference. What is resistance of a conductor? What is electric power? Write three formulae used to find electric power.

The potential difference between two points is said to be one volt ( 1 V ) , if 1 Joule ( 1 J ) of work is done to move a charge of 1 Coulomb ( 1 C ) from one point to another point in a current-carrying conductor. The device used to measure electric potential difference is voltmeter. The property of a conductor to oppose the flow of charge through it is called its resistance. The SI unit of resistance is Ohm ( Ω ) . The rate of electrical work done per unit time is called electric power. The following are the three formulae used to find electric power. 1) P = V I where ‘ V ’ is the potential difference in volts and ‘ I ’ is the current in amperes 2) P = I 2 R where I is the current and R is the resistance 3) P = V 2 R where V is the potential difference and R is the resistance

Observe the given circuit diagram. Calculate the total resistance and the total current flowing through the circuit.

Given, R 1 = 5 Ω , R 2 = 4 Ω , R 3 = 12 Ω , V = 24 V We have to find the total resistance of the circuit ( R T ) and the total current flowing through the circuit ( I ) . The total resistance of the circuit, R T = R 1 + [ 1 R 2 + 1 R 3 ] R T = 5 Ω + [ 1 4 Ω + 1 12 Ω ] R T = 5 + [ 3 + 1 12 ] R T = 5 + 4 12 R T = 5 + 1 3 R T = 5 + 3 [ 1 R p = 1 3 , R p = 3 Ω ] R T = 8 Ω According to Ohm's law, the total current flowing through the circuit, I = V R T I = 24 V 8 Ω = 3 A Therefore, the total current flowing through the circuit is 3 A .

Draw the diagram of an electric circuit in which the resistors R 1 , R 2 and R 3 are connected in parallel including an ammeter and a voltmeter and mark the direction of the current.

The following is the diagram of an electric circuit with three resistors connected in parallel. In this diagram, A represents ammeter and V represents voltmeter. I represent the current flowing in the circuit. When the resistors R 1 , R 2 and R 3 are connected in parallel, the equivalent resistance is given by, 1 R p = 1 R 1 + 1 R 2 + 1 R 3 Here, the main current divides itself into different currents flows through each resistor. This means that, the currents in a resistor is inversely proportional to its resistance. The potential difference across each resistor is the same and is equal to that across the combination.

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 12 - Electricity>Karnataka Board-2018>Q 8

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Write the circuit symbol of p-n-p transistor.

Important Questions on Electricity

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 12 - Electricity>Karnataka Board-2019>Q 3

According to Joule’s law of heating, mention the factors on which heat produced in a resistor depends. According to this law write the formula used to calculate the heat produced.