When you walk on a woolen carpet and bring your finger near the metallic handle of a door an electric shock is produced.
Charge in transferred from your body to the handle
Understanding Static Electricity and Electric Shock
When you walk on a woolen carpet, friction occurs between the soles of your shoes (or feet) and the carpet fibers. This process is known as the triboelectric effect. The triboelectric effect is a type of contact electrification in which certain materials become electrically charged after they come into frictional contact with a different material.
Why Walking on a Carpet Creates Charge
Materials have different tendencies to gain or lose electrons when rubbed together. Wool and typical shoe sole materials (like rubber or synthetic materials) are far apart on the triboelectric series, meaning one tends to lose electrons and become positively charged, while the other tends to gain electrons and become negatively charged. In this case, walking on a woolen carpet often causes your body to accumulate a net electric charge.
- Friction between shoes/feet and carpet.
- Electron transfer due to material properties (triboelectric effect).
- Body accumulates a static electric charge (either positive or negative depending on the materials).
- This charge is stored on your body.
What Happens When You Touch a Metallic Handle?
A metallic door handle is a conductor. When your body, carrying a significant static charge, comes close to a conductor like a metallic handle, there is a strong potential difference between your body and the handle. If the potential difference is large enough, the accumulated charge on your body rapidly transfers to the handle. This sudden transfer of charge is an electric current, and it causes the sensation of an electric shock.
The discharge happens because the charges try to neutralize the potential difference. The path of least resistance is often through your finger to the metallic handle.
Analyzing the Options
Let's look at the given options:
| Option | Analysis |
|---|---|
| Charge in transferred from your body to the handle | This accurately describes the static discharge process. The accumulated charge on your body jumps to the conducting handle. |
| A chemical reaction occurs when you touch the handle | An electric shock from static electricity is a physical phenomenon involving the movement of electric charges, not a chemical reaction. |
| The temperature of the human body is higher than that of the handle | While there might be temperature differences, this relates to heat transfer (conduction, convection, radiation), not electric shock caused by static charge buildup and discharge. |
| The human body and the handle arrive at thermal equilibrium by the process | Thermal equilibrium refers to the state where two objects in contact reach the same temperature. This process is about heat transfer, not the transfer of electric charge causing a shock. |
Based on the physics of static electricity and discharge, the electric shock you feel is a direct result of the rapid transfer of electric charge from your charged body to the conductive metallic handle.
Revision Table: Static Electricity Concepts
| Concept | Brief Explanation |
|---|---|
| Static Electricity | An imbalance of electric charges within or on the surface of a material. The charge remains stationary (static) until it finds a path to discharge. |
| Triboelectric Effect | Charging by friction. When two different materials are rubbed together, electrons are transferred from one material to the other. |
| Electric Discharge | The sudden flow of electric current through a medium (like air) or a conductor (like your body and the handle) to neutralize a static charge buildup. This is often seen as a spark or felt as a shock. |
| Conductor | A material that allows electric charge to flow easily through it (e.g., metals like the door handle). |
Additional Information on Static Shock
The intensity of the shock depends on several factors:
- Amount of charge: The more charge accumulated, the larger the potential difference and the stronger the discharge. Humidity affects charge buildup; lower humidity (drier air) allows charges to build up more easily.
- Resistance of the path: The resistance of your body and the connection to the handle affects the current flow.
- Speed of approach: Approaching slowly can sometimes allow the charge to dissipate gradually through the air or other less noticeable means before direct contact is made.
Walking on certain types of carpets, especially in dry conditions, is a common way to build up a static charge on your body. Touching a grounded object or a large conductor like a metallic door handle provides a path for this charge to quickly discharge, resulting in the familiar static shock.
Similar Questions
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Important Questions from Electric Charge
Which of the following expressions correctly represents the SI unit of electric charge, the Coulomb ($C$), in terms of other fundamental or derived SI units?
- Suppose every second 1016 electrons come out of a body and move to another body, then the time is required to get a total charge of 3.2 C on the other body is:
- An object is found to have a net negative charge of $-5 \text{ nC}$. How many excess electrons are present on the object? (Given: elementary charge $e = 1.6 \times 10^{-19} \text{ C}$)
- A metallic sphere, initially possessing a positive electric potential relative to the Earth, is connected to the Earth by a conducting wire. Which of the following accurately describes the primary charge movement that occurs until equilibrium is reached?
Two point charges, $Q_1 = +3 \mu C$ and $Q_2 = -8 \mu C$, are placed at a certain distance apart. They attract each other with a force of $48 N$. If each charge is given an additional charge of $+6 \mu C$, what will be the magnitude and nature of the new force between them?
