A music system draws a current of 400 mA when connected to a 12 V battery.
(a) What is the resistance of the music system ?
(b) The music system if left playing for several hours and finally the battery voltage drops and the music system stops playing when the current drops to 320 mA. At what battery voltage does the music system stop playing.

Question

A music system draws a current of 400 mA when connected to a 12 V battery.
(a) What is the resistance of the music system ?
(b) The music system if left playing for several hours and finally the battery voltage drops and the music system stops playing when the current drops to 320 mA. At what battery voltage does the music system stop playing.

KnowledgeBoat · Accepted Answer

Given, I = 400 mA = 400 x 10^-3 = 0.4 A V = 12 V From Ohm's law, V = IR Substituting the values in the formula we get, Hence, the resistance of the music system = 30 Ω (b) Given, I = 320 mA = 320 x 10^-3 A = 0.32 A R = 30 Ω From Ohm's law, V = IR Substituting the values in the formula we get, V = 0.32 x 30 = 9.6V Hence, the battery voltage when the music system stops playing = 9.6 V

Physics

Current Electricity

Related Questions

A battery of e.m.f. 6.0 V supplies current through a circuit in which resistance can be changed. A high resistance voltmeter is connected across the battery. When the current is 3 A, the voltmeter reads 5.4 V. Find the internal resistance of the battery.

A cell of emf 1.8 V and internal resistance 2 Ω is connected in series with an ammeter of resistance 0.7 Ω and resistance of 4.5 Ω as shown in figure.
(a) What would be the reading of the ammeter?
(b) What is the potential difference across the terminals of the cell ?

A cell of e.m.f. ε and internal resistance r sends a current of 1.0 A when it is connected to an external resistance of 1.9 ohm. But it sends a current of 0.5 A when it is connected to an external resistance of 3.9 ohm. Calculate the values of ε and r.

Two resistors having resistance 8 Ω and 12 Ω are connected in parallel. Find their equivalent resistance.