a) Define electric current. What is the SI unit of electric current?b) One coulomb of charge flows through any cross-section of a conductor in 1 second. What is the current flowing through the conductor?c) Which instrument is used to measure electric current? How should it be connected in a circuit?d) What is the conventional direction of the flow of electric current? How does it differ from the direction of the flow of electrons?e) A flash of lightning carries 10C of charge which flows for 0.01s. What is the current? If the voltage is 10MV, what is the energy?

a) Electric current is defined as the flow of electric charge in a conductor. It is measured in amperes. Its symbol is A.

b) One coulomb of charge flows through any cross-section of a conductor in 1 second is one ampere.

Mathematically, 1 A = 1 C/s.

c) Ammeter is used to measure electric current. To find the amount of current flowing through the circuit, it must be connected in series and must have less resistance.

d) The conventional current flows from the positive terminal of a cell to the negative terminal. However, the actual electron flow is from the negative terminal to the positive terminal of a cell, which is the opposite direction of that of a conventional current.

e) Given: The charge of lightning =  10C.

The charge has flowed for = 0.01s

The voltage of the lightning = 10MV

To find: We have to find the current and the energy of the lightning.

Solution: 

We know that, 

$I=\ \frac{Q}{ \begin{array}{l}
t\\
\end{array}}$

=> $I=\ \frac{10}{ \begin{array}{l}
0.01\\
\end{array}}$

=> I = 1000A

We know that, 

$v=\ \frac{W}{ \begin{array}{l}
C\\
\end{array}}$

=> 10,000,000 = $\frac{W}{ \begin{array}{l}
10\\
\end{array}}$

=> W = 10⁷J or 100MJ.

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Updated on: 10-Oct-2022

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