chapter 18 dc circuits Flashcards
current in series circuit
remains constant throughout
emf in series circuit
emf of source = PD1 of component 1 + PD2 of component + … + PDn of component #
at each component emf decreases as component uses up to their PD
by time after last component, emf = 0
resistance in series circuit
Rtotal = R1 + R2 + … + Rn
current in parallel circuit
Current of source/Itotal = I1 of component 1 + I2 of component 2 + .. = Current after wires split up (eg I1 + I2 = I3 after the split wires = I of battery)
emf in parallel circuit
equal in each component attached in the split wires
resistance in parallel circuit
Rtotal in split wires: (1/R1 + 1/R2 +..)^-1
If there are components after/before the split wires, just add the resistance like in series
potential divider (rheostat)
line of resistors connected in series = provide a fraction of voltage of a source to another part of circuit
1. total emf in circuit = Vin = emf of dry cell = pd of R1 + pd of R2
2. current across all resistors are constant (I = Vin/R1+R2)
3. Vout (pd being supplied out of the circuit) = PD of resistor Vout is connected in parallel with [Vout = IR (of resistor) = (Vtotal/R1+R2) x R2]
potentiometer
change the length of resistance wire (by slidng jockey) to change resistance across Vout
formula: AC/AC+BC x Vcell (since when length increases, R increases, shorter the lenght is nearer to Vout, higher resistance)
thermistor (th)
converts thermal energy to electrical energy\
1. temp increase, Rthermistor decreases but Rresistor remains same = Rtotal decrease = current in circuit increase (since I = V/R)
2. Vout is parallel to fixed resistor
3. Vout = Rresistor/(Rtotal) x Vin
light dependent resistor (ldr)
converts light energy to electrical energy
1. light intensity increase, Rldr decrease but Rresistor constant = Rtotal decrease = Itotal increase
2. Vout parallel to fixed resistor
3. Vout = (Rresistor/Rtotal) x Vin
