DC Theory final test

questions involving dc theory and basic circuit drawings

which particle carries a positive electrical charge?

Proton

• electron carries negative charge

• neutron carries no charge

equation for total resistance in parallel when 2 resistors exist

only when 2 resistors exist, when more are present use 1/R1 + 1/R2 ect.

when parallel contains 2 branch circuits with each containing resistors in sires, how should you go about solving for current?

first find current in each branch separately, then add both branches current to find total current in the circuit

which unit is used to measure electrical power?

Watts or use the symbol P for power

what happens to total resistance when another resistor is added in series?

resistance is increased in series with an added resistor

how does current through each component compare in a series circuit

the electrical current stays the same through every component.

three resistors in parallel, how to find current through each resistor?

1/r1 + 1/r2 + 1/r3…. Flip final answer then solve, = Rt, use Rt to find current

why are over current protection devices such as fuses and circuit breakers necessary?

to protect devices from over current, overheating and wire damage, to equipment and electrical fires.

what is an electrical overload?

when equipment takes on excessive load current that can overheat conductors and damage devices.

calculate resistance?

V/A voltage/current

what happens to total resistance when another resistor is added in parallel?

resistance increases in parallel

which symbol represents electrical current

I or A for amps

2 resistors are connected in parallel, what voltage would flow between both resistors?

both would receive the same voltage, only changes when resistance is applied and ohms law is used. and voltage drop is applied.

no

yes

electrical power is best described as?

electrical circuit transfer rate, rate its consumed, or converted

with resistance held constant, how does the rate of resistive heat production change as current increases?

increases to the Current squared

how to find current?

Voltage/Resistance, V/R=I

voltage is best described as?

potential current that can pass at 2 points, or difference of the points.

find voltage?

IxR=E, Current x Resistance = voltage

a circuit with 1 resistor in sireis with 2 resistors in parallel, how would current be found with resistance?

if 2 parallel use (r1xr2)/(r1+r2) and add remaining resistors in series, solve for current, if parallel has more than 2 use normal reciprocal method to find resistance.

if a parallel has an unknown resistor value, how would you find it when given 1 resistor, voltage, and current.

if 1 resistor is known, find that total current draw, what’s left over use to find other resistors vale.

how does direct current (DC) flow through a circuit?

it runs constantly in on direction, through a closed circuit.

which formula describes resistive heating caused by current?

what is electric current in a metallic conductor

ordered, directional flow of free electrons

how to find total resistance in series?

add all values of resistors R+R+R…= Rt

which equation correctly expresses ohms law?

V=I x R

find current in a parallel circuit with 2 resistors whit both known and voltage known?

find current in both separate branches, add both currents for total current in circuit.

2 conductors have same properties, but 1 is longer that the other, how does resistance compare?

the longer one has more resistance, if its twice as long, resistance is doubled.

Fleming left hand rule is used to determine?

the direction of the force acting on a current carrying conductor placed within a magnetic field

what is the symbol for electrical resistance

OMEGA symbol, or R for resistance

a short circuit is best described as?

when current flows an unintended low resistance path instead of traveling through the proper circuit.

when resistance increases, what happens to current?

current increases

go find a missing resistor problem online, where a resistor is left unknown.

find voltage drop?

multiply that branches current drop by V=IR, find that resistors separate voltage received.

equation for resistance in sires

r1+r2+r3….. = Rt equation for sires

find total resistance in parallel circuit?

use 1/R1 + 1/R2 + 1/R3….. then find common denominator, add all together, flip what’s left and solve for final numerical value.

a 3 ohm resistor connected in series with a 6 and 12 ohm resistor in parallel, with 42 V, how to find current in the parallel resistors?

find parallel resistance, add series, find total current then current flow in each resistor. 3 hom, 6 ohm and 12 ohm,

find current?

v/r=i

why does a loose electrical connection often overheat?

with a loose meatal to meatal contact, there is less area for electrons to flow from, making the spots that are connected to crowd electrons and forcing them through causing heat to build up in those areas.