Physics Chapter 11: Practical Circuits

 PHYSICS KEYWORD LIST:

Internal Resistance: Internal resistance of a source of EMF is the resistance inherent in the source itself; some energy is transferred into other forms as work is done in driving charge through the source itself.

Terminal p.d: Potential difference across the terminals of a source and is dependent on the current that is taken from the source.

Potential Divider: Circuit that splits the potential difference (V) from a source into 2 parts, so that the p.d. across one section is V₁ and the p.d. across the other section is V₂, where V₁ + V₂ = V.

Potentiometer: Device used for comparing potential differences.

Sensor or transducer: Electronic component with a property that changes when a physical quantity such as temperature or light intensity alters.

Galvanometer: Instrument used to measure or detect small electric currents. It is often not calibrated. By adding resistors in series or in parallel with it, and with suitable calibration, it can act as a voltmeter or an ammeter, respectively.

Null Method: Experimental technique where a zero reading is sought. The word ‘null’ comes from the Latin ‘nullus’ meaning ‘not any more’ or ‘nothing’.

 

PHYSICS CHAPTER WISE SUMMARY:

A source of emf such as a battery has an internal resistance. We can think of the source as having an internal resistance, r, in series with an emf E.

The terminal p.d. of a source of emf is less than the emf because of the potential difference across the internal resistor: terminal p.d. = emf – p.d across the internal resistor. (V = E – Ir)

A potential divider circuit consists of 2 or more resistors connected in series to supply. The output voltage V_out  across the resistor of resistance R₂ is given by:  V_out = ((R₂)/(R₁ + R₂)) x V_in.

A potentiometer can be used to compare potential differences.

 

PHYSICS IMPORTANT NOTES:

The potential difference across a power source: V = E – Ir

Potential Divider equation: V_out = ((R₂)/(R₁ + R₂)) x V_in