REVIEW HW ELECTRICITY
The electrical force btw 2 objects depends on
(2 of the above) distance btw/charge of objects
a system w/ 8 E, and 4 neutrons has a charge of
-12.8x10^-19
a system of 16 E, 11 P, and 1 N has a net charge of
-8x10^-10 C
A component of an automobile 12-v electrical system has a resistance of 30. how much current?
.4A
Two 60-watt light bulbs are connected in parallel across a 120-V power line. The current in each bulb is
.5A
Two charges repel each other with a force of 10-6 N when they are 10 cm apart. When they are brought closer together until they are 2 cm apart, the force between them becomes
2.5 x 10-5 N.
AN insulator has a (+) charge of 4x10^-17 C. HOw many electrons were added/removed?
250 removed
The voltage needed to produce a current of 8 A in a resistance of 12 ohms is
96 volts
If you rub a balloon on your sweater and then press it to a wall, it will often stick there. Why does this happen?
It Charges it electrostatically-induces opposite charge on wall
THe mathematical form of coulombs law is similar to
Law of gravition
Which of the following are NOT true?
Protons and electrons have equal masses
For an ohmic conductor, current is
inversely proportional to resistance
Earths magnetic field
is believe to arise from currents within planet's core
A ferromagnetic material loses this property above
the curie temp.
If the voltage across a resistor doubles
the current doubles
Direct electric current CAN be used
to operate electric motors
The electrical power dissipated in an appliance depends on
voltage,current,&resistance
If a (-) object is brought near a suspended, (+) object, the suspended obect
will be attracted
A system of an electron, a proton, and a neutron has a net charge of
zero
The current in a 24-W, 12-V light bulb is
2 A
The power rating of an electric motor that draws a current of 3 A when operated at 240 V is
720 watts
The current in a 20-ohm electric heater operating at 220-V is
12A
Three resistors 40, 60, & 50 are wired as a series and connect to a 120-V battery. WHat is equivalent resistance for this circuit?
150
Two charges, one positive and the other negative, are initially 2 cm apart and are then pulled away from each other until they are 8 cm apart. The force between them is now smaller by a factor of:
16
which would be the least conductive
Glass
Ohm's law gives the relationship between
current and voltage
In a battery circuit w/ different resistors in parrellel..
The voltage is the same across each resistor
If work is done on an electrical charge
a voltage is present
The nucleus of an atom
contains most of the atoms mass
ELectricity charge is measure in units of..
coulombs
IF you were to cut a bar magnet in half
each piece would be small bar magnet with a north & south pole
A motor converts
electrical energy into mechanical energy
Atoms and molecules are normally
electrically neutral
A current flowing thru a copper wire (which is connect to a battery) is due to
electrons being accelerated by an electric field
In a conductor
electrons moves
A kilowatt hour is in units of
energy
Ohms law holds only
for metals
A generator is a device that converts
mechanical energy into electrical energy
If 2 macroscopic objects are electrically attracted to each other
one object is (-) & the other is (+)
The volt is the unit of electric
potential difference
Magnesium
results from the movement of electric charge