posted by priya .
An automobile battery has an emf of 12.6 V and an internal resistance of 0.0500 . The headlights together present equivalent resistance 5.60 (assumed constant).
(a) What is the potential difference across the headlight bulbs when they are the only load on the battery?
(b) What is the potential difference across the headlight bulbs when the starter motor is operated, taking an additional 35.0 A from the battery?
a. I=E/(Ri+Rb) = (12.6/(0.05+5.60)=2.23A
V = I*Rb = 2.23 * 5.60 = 12.49 Volts.
b. Vb=E-I*Ri=12.6 - (35+2.23)0.05=10.74
(from chapter 12) At a temperature of 0 °C, the mass and volume of a fluid are 825 kg and 1.17 m3. The coefficient of volume expansion is 1.26 × 10 – 3(C ° ) – 1. (a) What is the density of the fluid at this temperature? (b) What is the density of the fluid when the temperature has risen to 20.0 °C?