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.

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.......

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