Physics Current Electricity Level: High School
The switch in the figure which is shown at ‘click here’ has been open for a long time . It is closed at t = 0 s . what is the current through the 20 ohm resistor,a) immediately after the switch is closed ?
b) after the switch has been closed a long time ?
c) immediately after the switch is reopened ?
Physics Current Electricity Level: High School
Which one of the following notes you can safely ignore ?a) Danger! Ten thousand volts !
b) Danger! Ten thousand Ohms !
c) Danger! Ten thousand Ohms !
d) None of the above .
e) All of the above .
Physics Current Electricity Level: High School
An automobile headlight and a dashboard light use the same voltage , but the power input to the headlight is much larger because .a) Its resistance is lower .
b) The current in it is larger .
c) It uses energy faster .
d) All of the above .
Physics Current Electricity Level: High School
A quantity that measure the rate of the charge flow isa) voltage
b) current
c) resistance
d) electric field
e) critical
Physics Current Electricity Level: High School
Eight light bulbs are connected in parallel to a 110-v source by two long leads of total resistance 1.6 if 250 mA flows through each bulb, what is the resistance of each bulb , what is their total resistance , and what fraction of the total power is wasted in the leads ?
Physics Current Electricity Level: High School
A 1.5 v dry cell can be tested by connecting it to a low-resistance ammeter. It should be able to supply at least 22 A . What is the internal resistance of the cell in this case , assuming it is much greater than that of the ammeter ?
Physics Current Electricity Level: High School
Lightbulb A is rated at 120 V and 40 W for household applications . Lightbulb B is rated at 12 v and 40 W for automotive applications .a) What is the current through each bulb ?
b) What is the resistance of each bulb ?
c) In one hour, how much charge passes through each bulb ?
d) In one hour, how much energy does each bulb use ?
e) Which bulb requires larger diameter wires to connect its power source and the bulb ?
Physics Current Electricity Level: High School
A hair dryer draws 7.5 A when plugged into a 120-v line .a) What is its resistance ?
b) How much charge passes through it in 15 min ? How many joules of energy used during this time ? (Assume direct current)
Physics Current Electricity Level: High School
From the figure which is shown at “click here” find the following :a) R total
b) I through 6 ohm
Physics Current Electricity Level: High School
From the figure which is shown at “click here” find the following :a) R total
b) I through the 4 Ohm resistor
c) I total
Physics Current Electricity Level: High School
From the figure which is shown at “click here” find the following :a) R total
b) I
c) Potential across the 4 ohm resistor
Physics Current Electricity Level: High School
A certain x-ray tube operates at a current of 10.4 mA and a potential difference of 84.4 kV . What is its power ?
Physics Current Electricity Level: High School
A common flashlight bulb is rated at 0.44 A and 2.5 V ( the values of the current and voltage under operating conditions) . If the resistance of the bulb filament at room temperature (20 degrees C) is 1.2 and #937; , What is the temperature of the filament when the bulb is on ? The temperature coefficient of resistance if 3.8 x 10-3 K-1 for the filament material .
Physics Current Electricity Level: High School
A coil is formed by winding 210 turns of insulated copper wire (diameter = 1.6 mm) in a single layer on a cylindrical form of radius 9.2 cm . What is the resistance of the coil ? Neglect the thickness of the insulation . (Take the resistivity of copper to be 1.69 x 10-8 ohm-m)
Physics Current Electricity Level: High School
A 0.8 mile long copper wire that has a resistance of 29 ohm is cut in half . What is the resistance of one of the halves ? Answer in units of Ohm .