पाँच प्रतिरोधक, जिनमें से प्रत्येक का मान 250 Ω है, समानांतर (parallel) में जुड़े हुए हैं। इस समानांतर संयोजन का प्रभावी प्रतिरोध ज्ञात कीजिए।

A DC source supplies a voltage of 15 V to two series-connected resistors, one of which is 7.5 Ω and the other is an unknown resistor R. If the total circuit current is 1 A, determine the value of the unknown resistance R.

A resistor of 10 Ω is connected to a constant voltage source. When another resistor is connected in series with it, the current in the circuit becomes half of its initial value. Assuming the supply voltage remains unchanged, the resistance of the second resistor is _______.