Consider the following circuit:If V1 = 5V and V2 = 3 V,

Consider the following circuit:

If V₁ = 5V and V₂ = 3 V, then what is the input impedance of the CRO in the above circuit?

The given circuit.

Let the input impedance of CRO is R₂ the given circuit can be redrawn as shown below

Applying voltage divider rule

V₂ = V₁ ×	R₂
	R₁ + R₂

3V = 5	V × R₂
	1 MΩ + R₂

or 5R₂ = 3 R₂ + 3
or 2R₂ = 3
or R₂ = 1.5 MΩ