Electric Circuits Answers

A cell with emf 15V and internal resistance 5.6 Ohms is connected in series to an ammeter and a 0-3.9MegaOhm variable resistor. A voltmeter is connected across the terminals of the cell..
a) Sketch the circuit diagram
b) Describe how this circuit can be used to obtain a value for the emf of the cell
c) Sketch and label the graph
d) Calculate the terminal voltage when a current of 87.9 microAmps is measured by the ammeter
e) Calculate the load resistance when a current of 55.8 microAmps is measured by the ammeter
f) Describe several limitations of this investigation

A lamp rated 120 watts and 240 volts what is its resistance

suppose electrical energy cost 25 cents per kilo watt hour. Calculate the cost of the electrical service to a house which uses four 40w hours and three 60w lamps for 100 hours

A.
Your refrigerator is located a bit too far away from the nearest electrical power point, so you use your 10m extension lead to connect the appliance. You leave the extension lead wound up in a coil. After 4 hours you notice that the extension lead if very warm but the appliance wire is not. Explain.

B.
A wire carrying 2 A DC will experience a pull to one side when the wire is carrying current in a strong external magnetic field. However, if that same wire were carrying 2 A AC instead, the wire does not experience any sideways pull. Explain.

C.
A standard household circuit that is rated for 10 A, how many 2000 W devices could be plugged in and operating at the same time without overloading the circuit?

A configuration of equipotential lines between positive and negative parallel plates is shown in the
figure below to the left. Calculate the magnitude of the electric field strength in the region between
the +18 V and +12 V equipotential lines.

Three point objects have electrical charges and locations, as shown in the figure below to the left.
(a) Calculate the electrical potential energy U for this three-charge system.
(b) Calculate the electric potential V due to this three-charge system at a point 10.0 cm
directly above the 3.00 μC charge.

HI i have a IR photobeam sensor(12vd) to trigger a alarm system if some one gains access to our rear yard across the path so if they walk through it triggers, my alarm sesnor operates on a NC system, its all set up but the alarm sensor that talks to the alarm (a standard magnetic door sensor type with wired contacts) . The alarm sensor needs the circuit to be open for longer than the photo sensor does when you brake the beam aprox time 0.5 secs, it needs approx 2 secs for the alarm sensor to register it as open, (as like when you open a door)

what would be needed to extend the trigger time from the photo sensor ? as it works well if you stand in the way of the beam but if you pass trough by walking the photo electric sensor triggers but the alarm sensor does not as its so quick.
A time delay is needed when circuit is open

1. A rectangular coil measuring 200 mm by 100 mm is mounted such
that it can be rotated about the midpoints of the 100 mm sides.
The axis of rotation is at right angles to a magnetic field of uniform
flux density 0.05 T. Calculate the flux in the coil for the following
conditions:
(a) the maximum flux through the coil and the position at which
it occurs;
(b) the flux through the coil when the 100 mm sides are inclined
at 45° to the direction of the flux

2. Three resistors of 6 Ω, 9 Ω and 15 Ω are connected in
parallel to a 9 V supply. Calculate: (a) the current in
each branch of the network; (b) the supply current;
(c) the total effective resistance of the network.

HOW op amps can be used as an INDUCTOR ? prove it mathematically

1.60 mm diameter tin cylindrical wire carries current of 4A. The drift velocity of the conduction electrons is 0.15 mms^-1. What is the concentration of conduction electrons?