As shown in the figure, a circuit consists of two ideal electromotive force (emf) sources and eight resistors. When the current flows through the resistor "R", it produces heat at a rate of 3.0 W. Find i) the value for the emf (E) and ii) the value of the positive terminal of the unknown power source.

A student made the electric circuit, as shown in the figure below, to measure the value of an unknown resistor, R_a, that is using ideal batteries. The red ammeter indicates a value of 2.25 A. Find the resistance of R_a.

Consider a circuit consisting of a 9.0-V battery, a 100.0 μF capacitor, a 60.0 Ω resistor, a switch, and an ammeter wired in series. Initially, the switch is open and the capacitor is totally discharged. The switch is closed, and after a time t, the ammeter shows a value of 0.05 A. Determine the charge Q on the capacitor at time t.

Both batteries in the figure below are ideal. The batteries E₁ and E₂ have a voltage of 8.0 V and 6.0 V, respectively. The resistors R₁ and R₂ have values of 25.0 Ω and 15.0 Ω, respectively. Calculate the current flowing through the resistor R₂.

The ideal batteries shown in the figure below are ideal and have electromotive forces E₁ and E₂. Calculate E₁ and E₂.

i) What is the expected reading of the ideal voltmeter in the figure shown if the switch S is open? i) Which point (M or N) has the greatest electrical potential?