Igcse Model Questions Vol1 2017 Physics Question 7
Practice objective / multiple choice question 7 from the 2017 Igcse Model Questions Vol1 Physics examination.
A 12 V battery has an internal resistance of 0.5 \(\Omega\) and is used to power a 6 \(\Omega\) lamp. An external resistor \(R_{\text{ext}}\) is connected in series with the lamp. Determine the value of \(R_{\text{ext}}\) (in \(\Omega\), to two decimal places) that will make the power dissipated in the lamp exactly half the power it would have when the lamp is connected directly to the battery (i.e., without \(R_{\text{ext}}\)). For this arrangement, also calculate the efficiency of the circuit, defined as the fraction of the total power supplied by the battery that is dissipated in the lamp, expressed as a percentage to one decimal place.
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About This Question
This is Igcse Model Questions Vol1 2017 Physics Question 7. It is one of the objective questions from the 2017 Igcse Model Questions Vol1 Physics examination.
Difficulty level: Hard .
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