Physics report NRT

Physics Report: NTC and LDR

Introduction:

With the fixed and variable resistor, we have to types of resistors. Resistors are also classified according to the material they are made up of, such as foil, carbon or grid. In this experiment we are going to focus on the resistors LDR (light dependent resistor) and NTC (negative temperature coefficient). The goal of the following experiment is to determine the characteristics of these resistors. We are going to determine those characteristics by measuring the resistance R of the NTC at different temperatures and the resistance of the LDR at different light intensities. I assume that the resistance of the NTC will increase with heat and decrease with cold. The resistance of the LDR will increase in the dark and decrease in the light.

Methods:

The serial circuit with V0=5V consists of two multimeters, one as an Ammeter to measure the current {I} and the other as a Voltmeter to measure the voltage {V}, a breadboard, the resistor (NTC or LDR) and an ohmic resistor in order to protect the resistor. With the NTC we are going to measure the voltage and current at a low temperature, using a cooler-spray to cool it down, at room temperature and at a high temperature, using a hair dryer to heat it up. Knowing that the LDR changes its resistance with light intensity, we are going to measure the voltage and current in normal daylight, in the dark and at a high light intensity, using a flashlight. In both cases we calculate the resistance as follows:

Resistance= Voltage divided by the current

Diagram of the NTC Circuit:                 Diagram of the LDR Circuit: [pic 1][pic 2]

Results:

[pic 3][pic 4][pic 5]

The resistance of the NTC decreases with an increase in temperature, whereas the current increases with an increasing temperature. Also noteworthy is that the resistance decreases with an increasing temperature.

[pic 6][pic 7]

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