Aptitude Test Problems in Physics Science for Everyone by S Krotov ( PDFDrive.com )

3. Electricity and Magnetism 83

3.28. The circuit diagram shown in Fig. 86

consists of a very large (infinite) number

of elements. The resistances of the resistors

in each subsequent element differ by a fac-

bp,

Fig. 86

for of k from the resistances of the resistors

in the previous elements.

Determine the resistance RAB between

points A and B if the resistances of the first

element are R 1 and R2.

3.29. The voltage across a load is controlled

by using the circuit diagram shown in Fig. 87.

The resistance of the load and of the

U I

X

Fig. 87

O

R

potentiometer is R. The load is connected

to the middle of the potentiometer. The in-

put voltage is constant and equal to U.

Determine the change in the voltage

across the load if its resistance is doubled.

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