Subject: Applied Physics 2

Topic: Motion Of Charged Particles In Electric And Magnetic Fields

Difficulty: Low

Measurement of DC voltage.:

Connect DC source to channel 1 on the front panel of CRO with CRO probe. The input coupling switch is kept in DC position. The trace on the screen is made to coincide with the central horizontal line. The Volt/div knob is kept at 1 volt/div and power supply is varied and its effect on the trace is noted. The trace moves upward with increase in voltage and downward with decrease in voltage. The amount of deflection in terms of number of division are noted and is multiplied with Volt/div knob. The value of Dc voltage is then calculated.

Measurement of Ac frequency: Time period measurement method:

The input coupling switch is kept in AC position. The function generator mode is kept as sinusoidal and is connected to channel 1 of CRO with the probe. An input signal of a particular frequency is given. Once the wave is observed on the screen the length of one wave is measured. This is multiplied by Time/div value. Reciprocal of this value is the frequency. F = 1 / T

Measurement of AC frequency: Lissajous pattern method:

The signal of unknown frequency is applied to the vertical input and a voltage of known frequency is given to the horizontal input. By varying the frequency of the known source,stable loop pattern known as Lissajous pattern is obtained on the screen. The number of points at which the loops touch the horizontal and vertical tangents is noted. If LH and LV are the number of points touching the horizontal and vertical tangents respectively, then the unknown frequency is calculated from Fy = Fx [ LH / LV ]. Fx is known frequency