## Title:- S.I Unit Of Resistance.

## Introduction:-

### Today I have come infront of you with a new topic S.I Unit of Resistance. which is related on a very important topic of physics 'Electricity' and todays discussion is very helpful for class (ix) and class (x) students.

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## Explanation:-

### To proceed our main discussion, Let, us quickly remember some basic knowledge,

## What is charge?

### Answer:- Charge is a physical property of matter which creats matter to experience a force when it is kept in an electromagnetic field. It is denoted by (q).

## What are the different types of charge ?

### Answer:- There are two different types of charges and they are :- (i) Positive charge which possess protons(+p) are always present at the centre or nucleus of an atom. (ii) Negative charge which posses electrons(-e) are always revolve in the extra nucleus or circular path which cover the nucleus of an atom.

## What is electricity ?

### Answer :-

### The flow of electric charge through a metallic conductor is called electricity.

## What is current or electric current

### Answer :- The flow charges per unit time though a metallic conductor is termed as current or electric current. It is denoted by (I).

Mathematically, Current can be expressed as ,

I = q / t

Where,

q = Charge

t = Time

In another way we can explain the rate of flow of electrons in a metallic conductor is termed as current.

## What is Ohm's law of electricity?

### Answer :- At constant, temperature and pressure the flow of current(I) through a metallic conductor is directly proportional to the potential difference(V) of its two ends, which is known as Ohm's law of electricity.

Mathematically, it can be expressed as,

I ∞ V

=> I = V/ R [ Where, R is a special constant of proportionality, is called resistance of the conductor.]

## What is resistance?

### Answer :-

### Resistance or electric resistance can be defined as the ratio between the potential difference to the current flowing through any conductor. It is denoted by 'R'

## What are the factors on which resistance of a conductor depends ?

### Answer:- The factors on which resistance of a conductor depends are :-

(i) Area of the cross section of conductor.

(ii) Material of the conductor.

(iii) Length of the conductor.

### Finally we will know,

## S.I Unit Of Resistance.

### Answer:- S.I unit of resistance is volt/ampere or ohm.

### Additionally we will learn,

## Some Problems related on resistance.

### (1) The resistance of an electric circuit is 5 ohm has a potential difference 10 volt, find the flow of current in the circuit.

### Answer:- Here,

Resistance of the circuit(R) = 5 ohm

Potential difference (V) = 10 volt

### ∴ Flow of current (I) = V/R

= 10/5

= 2 Ampere

### (2) The flow of current through a circuit is 10 ampere, having a 2 ohm resistor connected with the circuit, find the potential difference.

### Answer:- ∵ Current (I) = 10 ampere

Resistor (R) = 2 ohm

∴ Potential diffence (V) = IR

= (10 × 2)

= 20 Volt

### (3) Three resistors 2 ohm, 3 ohm and 4 ohm are connected in series in an electric circuit. Find the equivalent resistor of the combination.

### Answer:-

Here,

R₁ = 2 ohm

R₂ = 3 ohm

R₃ = 4 ohm

∵Resistors are connected in series

Let, the equivalent resistance of the combination = R

∴ R = ( R₁+ R₂ + R )

= ( 2 + 3 + 4) ohm

= 9 ohm

∴ Equivalent resistance of the circuit (R)= 9 ohm.

### (4) Three resistors 2 ohm, 4 ohm and 6 ohm are connected in parallel in an electric circuit. Find the equivalent resistor of the combination.

### Answer:-

Here,

R₁ = 2 ohm

R₂ = 4 ohm

R₃ = 6 ohm

∵Resistors are connected in parallel.

Let, the equivalent resistance of the combination = R

∴ 1/R = 1/R₁ + 1/ R₂ + 1/ R₃

= ½ + ¼ + ⅙

= ( 6 + 3 + 2) /12 [ ∵ L.C.M of 2, 4 and 6 is 12]

= 11 / 12

∴ R = 12/11

= 1.090909…

= 1.1 ohm (approximately.)

## Conclusion:-

### From the above discussion we have known S.I Unit Of Resistance. Resistance and Electricity are co related. Without resistance we can't imagine the smooth flow of electricity ..........

.## FREQUENTLY ASKED QUESTIONS:-
## What is the SI unit of resistance and resistivity?

Answer:- The S.I unit of resistance is ohm and S.I unit of resistivity is ohm-meter.

## What is resistance unit and formula?

Answer:- Resistance unit is ohm and its formula,
R = V/I , Where R = Resistance, V = Potential difference and I = Current.

## What is the symbol and unit of resistance?

Answer:- The symbol of resistance is omega (Ω) and its unit is ohm.

## What is meant by 1 ohm?

Answer :- When a current of 1ampere flows through a metallic conductor through an electric circuit having a potential difference 1volt , then the resistance which is produced in the circuit is known as 1 ohm.
Mathematically, when
V = 1 volt
I = 1 Ampere
∴ R = V/ I
= 1/1
= 1 ohm

##
What is the symbol of current?

.Answer:- Current is denoted by 'I'.

## What is the SI unit of resistance and resistivity?

Answer:- The S.I unit of resistance is ohm and S.I unit of resistivity is ohm-meter.

## What is resistance unit and formula?

Answer:- Resistance unit is ohm and its formula, R = V/I , Where R = Resistance, V = Potential difference and I = Current.

## What is the symbol and unit of resistance?

Answer:- The symbol of resistance is omega (Ω) and its unit is ohm.

## What is meant by 1 ohm?

Answer :- When a current of 1ampere flows through a metallic conductor through an electric circuit having a potential difference 1volt , then the resistance which is produced in the circuit is known as 1 ohm. Mathematically, when V = 1 volt I = 1 Ampere ∴ R = V/ I = 1/1 = 1 ohm

## What is the symbol of current?

.Answer:- Current is denoted by 'I'.