Electricity

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Common Misconceptions

8 min read

- Let's bust come common misconceptions!

Is the direction of current in a closed circuit the same as the direction of electrons?

MYTH: Current flow direction is the same as the direction of electron flow

FACT: Conventional current flow direction is the opposite of the direction of negative charge carriers in a circuit

Conventional current flow direction is taken to be from the positive terminal of the cell to the negative terminal of the cell in a closed circuit that is opposite to the direction of electron flow

If electric cells produce electricity, does the cell contain lots and lots of electrons?

MYTH: Electric Cells are sources of electric charges

FACT: Electric Cells are sources of a constant Potential Difference, not charges

An electric cell is a device which when connected to a circuit across its terminals makes the electric charges present in the circuit elements and wires to move along a particular direction (from negative to positive terminal). Electric cells do not start emitting charges to a circuit.

Do batteries run out of charge?

MYTH: Batteries are rechargeable

FACT: Batteries are not rechargeable

When a battery dies, it has not run out of charges but the chemical reaction inside of the cell that generates potential difference across the terminals has stopped. When batteries are said to be recharged by devices, we are simply kickstarting those reactions again to generate a potential difference. Let's check out a video to learn more about the batteries.

Working of Dry Cell- Everyday Science

3 mins

A bulb lights up almost instantly when connected to a circuit. Are electrons lightning-fast?

MYTH: A bulb lights up when electrons from the negative terminal reach the bulb

FACT: Bulb lights up due to a constant flow of charges through the filament, and not because of electrons from the cell reaching it

When a bulb is connected to a battery, a flow of electrons is started, such that, if an electron from the negative terminal moves to the connecting wire, a free electron from the wire moves to the positive terminal of the cell, at the same time. Thus, it's the flow of electrons, that we call electric current which finally lights up the bulb.

If a bulb has a higher resistance, will it grow brighter?

MYTH: High Resistance Bulbs glow brighter

FACT: Low Resistance bulbs glow brighter

It seems logical to deduce that, higher the resistance of a filament, the more heat and light will be dissipated by it, and it will glow brighter. That is far from true. The consequence of having a high resistance filament in the circuit is, very low current flows through the circuit and there isn't much energy to dissipate. However, a filament with a lower resistance will lead to a high current passing through the circuit with high energy to dissipate. As a result, the bulb glows brighter.

Is Ohm's Law universally applicable?

MYTH: Ohm's Law is universal

FACT: Ohm's Law can be applied to certain kind of conductors, which we call Ohmic conductors

Ohm's Law cannot be applied to all conducting elements, i.e., the V-I characteristics of all conductors are not a straight line. Diodes, vacuum tubes, electrolytes, and several other conducting elements do not follow ohm's law.

High Voltage or High Current: Which one is deadlier?

MYTH: Only High Voltage can cause severe electric shocks

FACT: High volume of current is more dangerous

Always remember, voltage is the cause and the electric current is the effect. It is ultimately the current or the flow of charges through the body that leads to severe electric shocks. It is possible to get severe electric shocks from low voltage appliances if large currents pass through our bodies. However, try to be careful around both, high voltage and high current.

Series Vs Parallel circuit

Often confused about the basic differences between series and parallel circuits? Let's sum up their differences.