## Ohms law derivation class 10 | State ohm’s law class 10

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**Ohms Law** is an important topic of the electricity chapter for class 10th. Many questions related to this topic such as Ohm’s law derivation, formula, Ohms law circuit diagram, graph, limitations of Ohms law, etc are asked in the class tenth board exam.

**Definition of Ohm’s law or State Ohm’s law | What is a Ohm’s law**

According to George Simon Ohm,

**Ohm’s law definition, ” The potential difference or voltage(V) across the ends of an Ohmic conductor is directly proportional to the current (I) flowing through the ohmic conductor, provided the physical condition remains constant or unchanged.”**

Here the physical condition means temperature, pressure, humidity, etc.

In other words, you can also define the Ohm law-

**“Ohms law states that the current flowing in a conductor is directly proportional to the applied voltage across the ends of the conductor at constant physical condition.”**

That means, **V ∝ I or I ∝ V**

** ∴ V = RI or I = V/ R **

Or, **V = IR ………..(1)**

Where, V = Potential difference across the ends of conductor,

I = current flowing through the conductor

R = proportionality constant also known as Resistance of the circuit.

From above equation- (1 )

The SI unit of the resistance is **Volt/Ampere** which is also known as “**Ohm**“. Resistance represents as by a symbol that is **“Ω” (Omega).**

**What is resistance definition in electricity?**

The meaning of resistance is barrier or obstruction. If you look at it from an electrical point of view, the barrier that arises during the flow of electric current in the conductor is called resistance.

Therefore, **“The measure of barrier or opposition to current flow in any conductor or circuit is resistance.” **

**Unit of electrical resistance = Ohm (Ω), ****Unit of voltage = Volt (V), **

**Unit of Electrical Current = Ampere (A)**

So,

**Definition of 1 Ohm:-**

“When the voltage at the ends of the conductor is 1 volt and the current flowing in the conductor is 1 amp, the resistance of the conductor will be 1 ohm.”

**Important Points related to resistance:- **

1. Resistance of a substance depends on the kind of substance and its physical conditions.

2. The resistance of metallic materials increases with increasing temperature.

[Example of metallic material – Copper, Aluminum, Gold]

3. Insulators have very high resistance because they do not have free electrons.

[Example of insulators – wood, plastic, rubber]

**Ohm’s Law Graph or V-I graph for resistance R**

**Relation between voltage and current for ohmic resistance:- **

A variable battery is connected to a resistive wire (R) and a key as shown in the image above. An ammeter is connected in series with the resistance. While a voltmeter is connected in parallel with resistance.

Suppose we have four batteries of 2 volts connected with resistance in series. Here, instead of resistance in the circuit, we can also use any bulb.

**Ohm’s law experiment:-**

**STEP-1:- **First, connect a single battery of 2 volts to the circuit as a source. Then take current and voltage readings in the circuit with the help of an ammeter and voltmeter. (Here I have taken the reading of ammeter and voltmeter 0.5 A and 2 Volt.)

**STEP-2:- **Now connect the two batteries to the circuit and note the respective values of the ammeter and voltmeter.

**STEP-3:- **Repeat the same process using three and four batteries in the circuit. Note all the respective readings of the ammeter and voltmeter of all phases in a table. (As you can see in the observation table below.)

**STEP-4:- **After taking all the readings, find the ratio of voltage and current for each step or phase.

**Observation Table:- **

S. No. |
No. of Batteries connect |
Voltage in voltmeter (V) |
Current in Ammeter (I) |
R = V/I |

A. | 1 | 2 V | 0.5 A | 4 Ω |

B. | 2 | 4 V | 1 A | 4 Ω |

C. | 3 | 6 V | 1.5 A | 4 Ω |

D. | 4 | 8 V | 2 A | 4 Ω |

**V-I graph ( Voltage and current graph for Ohmic conductor)**:-

Now from the observation table draw the graph of voltage (on the y-axis) vs current (on the x-axis). You will get the following result.

**V-I graph characteristics **

1.) This graph will be of a linear equation that will pass through the origin.

2.) The V-I graph will be a straight line.

3.) As the value of voltage increases in the circuit, the value of the current will also increase in the same proportion.

4.) The ratio of voltage and current will remain constant in all phases.

**Limitations of ohms law**

1.) Ohms law is applicable to Ohmic conductors. For example – Copper, Aluminium, Silver

2.) Ohms law is not applicable for semiconductors (Diode & Transistor). Because after a certain voltage there is a sudden rise in current which violates the linear equation of Ohm’s law.

3.) Ohms law is not valid when the physical conditions (temperature) vary. So, it is only applicable at a constant temperature.

4.) According to the heating effect of electric current, a straight line gets a curve after a certain high temperature. So, Ohm’s law fails for Ohmic conductors at high temperatures.

**Application of Ohm’s law:-**

1.) With the help of Ohms law, we can determine the value of Voltage, current and resistance in an electrical circuit.

2.) Ohms law is used for electrical circuits. With the help of the Ohms law equation V=IR, we can determine the equivalent resistance series and parallel circuits.

3.) Ohms law is also used to balance or maintain the desired potential or voltage drop across the electronic elements.

4.) Ohms law is used for making Fuses of required resistance for the protection of home appliances.

**Some important questions related to Ohms law**

**Ques-1:- If an electric bulb connected to a 220 V line draws an electric current of 2 A, then what will be the resistance of bulb filament?**

Given that, Voltage V = 220V, Electric current I= 2A

Then according to ohms law,

**R = 220/2 = 110 Ω** (Ans)

**Ques-2:- The resistance of one conducting wire is 10 Ω. How much electric current will flow by connecting it with a battery of 1.5 V?**

Given that, Voltage V = 1.5 V, Resistance R = 10 Ω

So, V = IR

1.5 = I x 10

I = 1.5/10 = 0.15 A

**FAQ related to **Ohms law derivation class 10 | State ohm’s law class 10

**1. What is Ohm’s law in simple terms? or What does Ohm’s law state?**

According to ohms law, **The potential difference across the ends of a conductor is directly proportional to the current flowing through the conductor, provided the physical condition (Temp) constant.**

V = IR where R is the resistance of the conductor.

**2.) What are the 3 forms of Ohm’s law?**

The three forms of ohms law are used to determine the value of voltage, current & resistance respectively.

1.) V = IR, 2.) I = V/R, 3.) R = V/I

**3.) What is the unit of resistance?**

The S.I unit of resistance R is Volt/Ampere or Omega(Ω)

**4.) How can you mean by 1 ohm?**

When the voltage drop across the ends of the conductor is 1 volt and the current flowing in the conductor is 1 amp, the resistance of the conductor will be 1 ohm.

1 Ohm = 1Volt / 1 Ampere

**5.) Is Ohm’s law a universal law?**

No, it is not a universal law, because ohms law is not applicable for diode, transistor and gas tube.

**6.) Is ohms law applicable to all conductors?**

No, it is not applicable for all conductors. Because for some metallic conductors its graph curves at high temperatures.

**7.) How is Ohm’s law used in real life?**

A) Regulating the speed of fans.

B) Used for the design of fuses to prevent home appliances.

C) Electric kettles, iron, heaters have too many resistors to limit the amount of current to provide the necessary heat.

**8.) What is an Ohmic conductor?**

The conductors that follow the Ohms Law are the Ohmic conductors.

** Conclusion:**– (Ohms law derivation class 10 | State ohm’s law class 10)

**ohm’s law circuit diagram class 10:-** This post covers only the important questions related to Ohms Law, which is very important for the class 10 boards. I hope whatever is covered you will understand. But still, if you have any questions related to Ohm’s Law, you can ask in the comment box.