he deflection plates in an oscilloscope are 10 cm by 2 cm with a gap distance of 1 mm. A 100 volt potential difference is suddenly applied to the initially uncharged plates through a 1000 ohm resistor in series with the deflection plates. How long do

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The deflection plates in an oscilloscope are 10 cm by 2 cm with a gap distance of 1 mm. A 100 V potential difference is suddenly applied to the initially uncharged plates through a 1000 Ω resistor in series with the deflection plates. How long does it take for the potential difference between the deflection plates to reach 95 V?

Explanation:

Given that,

The dimension of 10cm by 2cm

0.1m by 0.02m

Then, the area is Lenght * breadth

Area=0.1*0.02=0.002m²

The distance between the plate is d=1mm=0.001m

Then,

The capacitance of a capacitor is given as

C=εoA/d

Where

εo is constant and has a value of

εo = 8.854 * 10-12 C²/Nm²

C = 8.854E-12*0.002/0.001

C=17.7*10^-12

C=17.7 pF

Value of resistor resistance is 1000ohms

Voltage applied is V = 100V

This Is a series resistor and capacitor (RC) circuit

In an RC circuit, voltage is given as

Charging system

V=Vo[1 - exp (-t/RC) ]

At, t=0, V=100V

Therefore, Vo=100V

We want to know the time, the voltage will deflect 95V.

Then applying our parameters

V=Vo[1 - exp (-t/RC) ]

95=100[1-exp (-t/1000*17.7*10^-12) ]

95/100=1-exp (-t/17.7*10^-9)

0.95=1-exp (-t/17.7*10^-9)

0.95 - 1 = - exp (-t/17.7*10^-9)

-0.05=-exp (-t/17.7*10^-9)

Divide both side by - 1

0.05=exp (-t/17.7*10^-9)

Take In of both sides

In (0.05) = -t/17.7*10^-9

-2.996=-t/17.7*10^-9

-2.996*17.7*10^-9=-t

-t=-53.02*10^-9

Divide both side by - 1

t = 53.02*10^-9s

t=53.02 ns

The time to deflect 95V is 53.02nanoseconds