How is LDR measured?

The LDR must be subjected to a bright light source (day light is enough). Connect the LDR leads to the multimeter terminals as shown in the figure. Now the multimeter will show a low resistance reading around 500 Ohms. Test2.

Is current measured across a resistor?

Resistors in series have the same current flowing through them. An ammeter, must be placed in series with a resistor to measure the current through the resistor.

What happens to the PD across the LDR and the current in the LDR?

As light intensity increases, distance decreases. As light intensity decreases, the LDR’s resistance increases, as does the potential difference across it. So, as distance increases, the potential difference increases.

What is the unit of LDR?

Measure Light Intensity using Light Dependent Resistor (LDR)

Parameter	Min	Unit
RL Light Resistance	20	kΩ
		kΩ

What happens to the current in the LDR?

The light energy produces more free electrons which increases the current for a certain voltage across the LDR which means a drop in resistance. In the DARK its resistance is LARGE (millions of ohms), in the LIGHT its resistance is SMALL (tens of ohms). Very little current will flow through it in the dark.

Where do we use LDR?

Applications of LDR These devices are used where there is a need to sense the presence and absence of light is necessary. These resistors are used as light sensors and the applications of LDR mainly include alarm clocks, street lights, light intensity meters, burglar alarm circuits.

How do you measure current in an AC circuit?

Current is usually measured by inserting a current transformer in the line side and monitoring the output with a 5A full-scale ac ammeter (fig. D). Where the circuit cannot be broken to insert the current transformer, a split core or clamp-on current transducer can be used.

How do you calculate electrical energy transfer?

The electric energy transferred to a resistor in a time period is equal to the electric power multiplied by time, E=Pt, and can also be calculated using E=I2Rt. Electric companies measure their energy sales in a large number of joules called a kilowatt hour (kWh) which is equivalent to 3.6×106 J.

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