Current Electricity Problems



Current Electricity Word ProblemsVariableVariable SymbolUnitUnit SymbolEnergyEjoulesJVoltage (Potential Difference)VvoltsVElectric ChargeQcoulombsCCurrentIamperesATimetsecondssFormula TrianglesEach formula triangle can be used to rearrange a formula to solve for each of the three variable’s. The horizontal line represents dividing and the vertical line represents multiply.VEQPotential DifferenceE = V x QV = E / QQ = E / VItQCurrentQ = I x tI = Q / tt = Q / ISOLVING ELECTRICITY PROBLEMSAll problems must be solved with the following steps to get full marks.1. State the variables given numbers and the unknown variable.2. Write the formula to use.3. Substitute the given numbers in to the formula.4. Solve.5. Check that units are written after every number because in science we measure real quantities.6. Check that all equations have variable symbols or numbers before and after the equal sign!!Sample Problems1. If 240 C of electric charge passes a certain point in a circuit in 5.0 minutes, what is the current through that point?Q = 240 CItQt = 5.0 min x 60 s /min = 300 sI = ?I = Q / t I = 240 C / 300 sI = 0.80 A2.Find the potential difference of a battery that uses 54 J of energy to energize 18 C of electric charge.VEQE = 54 JQ = 18 CV = ?V = E/QV = 54 J / 18 CV = 3 VCurrent Electricity Word ProblemsVariableVariable SymbolUnitUnit SymbolEnergyVoltage (Potential Difference)Electric ChargeCurrentTimeFormula TrianglesEach formula triangle can be used to rearrange a formula to solve for each of the three variable’s. The horizontal line represents dividing and the vertical line represents multiply.Potential DifferenceE = V =Q = CurrentQ = I = t = SOLVING ELECTRICITY PROBLEMSAll problems must be solved with the following steps to get full marks.1. State the variables __________________________________________2. Write the ___________________ to use.3. ____________________ the given numbers in to the formula.4. ________________________.5. Check that ___________________________ are written after every number because in science we measure real quantities.6. Check that all equations have variable symbols or numbers ________________________ and __________________ the equal sign!!SAMPLE PROBLEMSItQ1. If 240 C of electric charge passes a certain point in a circuit in 5.0 minutes, what is the current through that point?VEQ2.Find the potential difference of a battery that uses 54 J of energy to energize 18 C of electric charge.Current Electricity ProblemsWrite a complete solution to each problem. Be sure to complete the triangles.Electric Current Problems:I = Q/t, t = Q/I, Q = I x tI = electric current measured in Amperes (A)Q = electric charge measured in Coulombs (C) t = time, measured in seconds (s)A lightning strike carries 5.0 C of charge in the 0.02 s it takes to reach the ground. What is the electric current carried by the lightning strike?A small electric motor draws a current of 0.40 A. How long will it take for 8.0 C of charge to pass through it?How much current is flowing through a light bulb when it takes 24 s for 18 C of charge to pass through its filament?Suppose your calculator requires 0.20 mA (= 0.00020 A, do you know why?) to operate, and that it will be on for 2.0 minutes while you solve this problem. What quantity of charge will flow during this time?Potential Difference (Voltage) ProblemsV = E/Q, Q = E/V, E = V x QV=potential difference in volts (V)\E=energy or work measured in Joules (J) Q=charge measured in Coulombs (C)Suppose that a 9.0 V battery delivers 4.0 C of charge. How much work is done on the charge by the battery?If the total current in (a) is 1.5 A, for how long was the battery used?What amount of energy does a kettle use to boil water if it has 800 C of charge passing through it with a potential difference of 120 V?A flash of lightning transfers 1.5 x 109 (=1,500,000,000) J of electrical energy through a potential difference of 5.0 x 10 7 (=50,000,000) V between cloud and ground. Calculate the quantity of charge transferred in the lightning bolt.Calculate the energy stored in a 9.0 V battery that can deliver a current of 5.0 mA (=0.005 A) for 2.0 x 103 s. ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download