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**I/GCSE Physics**** Question Analysis Topic: Chapter 2: Electricity - Energy and Voltage in Circuits (Part 2)**

For I/GCSE Physics, you should know:

Now, let's learn about the second part IGCSE Physics Chapter 2 sub-topic on "Energy and Voltage in Circuits."__Qualitative Effect of Changing Resistance on Current:__

- As the
**resistance**in a circuit**increases**, the**current decreases**. - This is due to Ohm's law, which states that the
**current**is**inversely proportional**to the**resistance**(I = V/R). - So, if the
**resistance**goes**up**, the**current**will go**down**, and vice versa.__Variation of Resistance in Components:__ **Light-Dependent Resistors (LDRs):**- The resistance of an LDR decreases as the illumination on the component increases.
- This makes LDRs useful for light-sensitive applications, such as automatic lighting controls.
**Thermistors:**- The resistance of a thermistor decreases as the temperature increases.
- Thermistors are used in temperature-sensing applications, such as in electronic devices to monitor and regulate temperature.
__Indicating the Presence of Current:__ - Lamps and Light-Emitting Diodes (LEDs) can be used to
**indicate the presence of current in a circuit**. - When current flows through these components, they emit light, providing a
**visual indication**of the circuit's operation.__Relationship between Voltage, Current, and Resistance (Ohm's Law)__: - Ohm's law states that the voltage (V) across a component is equal to the current (I) flowing through it multiplied by the resistance (R) of the component.
- The mathematical expression for Ohm's law is:
**V = I × R**__Current as the Rate of Flow of Charge:__ - Current is the
**rate of flow of electric charge**through a circuit. - The unit of current is the
**ampere (A)**, which represents the flow of one coulomb of charge per second.__Relationship between Charge, Current, and Time:__ - The total charge (Q) that flows through a circuit is equal to the current (I) multiplied by the time (t) over which the current flows.
- The mathematical expression for this relationship is:
**Q = I × t**

Work hard for your I/GCSE Physics examination!

End of analysis. Great!