need help

https://en.m.wikipedia.org/wiki/Kirchhoff%27s_circuit_laws https://en.m.wikipedia.org/wiki/Ohm%27s_law https://en.m.wikipedia.org/wiki/Superposition_theorem https://en.m.wikipedia.org/wiki/Network_analysis_(electrical_circuits)

Good luck :)

This is a basic series circuit good for practicing ohms law. First you find the Vt (Total Voltage) which is 3V, it's 3V because if you look at the batteries if the negative signs are pointing to each other (Look at 6V and 15V battery) the voltage subtracts but if you have the negative signs following each other (for example turn the 15V 180 degrees around) then the voltages add up. So in this case the voltage on each battery subtract because of the way they are placed in the circuit with the negative sign facing each other so 6V-15V-10V-4V = -3V. Now to find resistance since its series resistance adds up so the Rt is 1,026 ohms. Now to find It (total current) = -3V/1,026 ohms = 2.92mA, since its a series circuit current stays the same through the entire circuit. so now you just do ohms law for each resistor. At 6 ohms * 2.92mA = 17.54mV (0.01754V), 4 ohms * 2.92mA = 11.68mV, 10 ohms * 2.92mA = 29.2mV, and 1K ohms * 2.92mA = 2.92V. Hope that helped.

To make sure you are right since its a series circuit use Kurchoff's law which is voltages around a loop add up to the total voltage so just say 2.92V + 17.54mV + 17.54mV + 11.68mV + 29.2mV = 2.99V (which is close to -3V).

To find out voltage at the voltmeter you would say 4V - 2.92V = 1.08V that is why the meter reads 1.08V and if the 1K resistor is not specified at what value (or for example 0 ohms) then that would change the Rt and the It therefore change the voltage calculations at each resistor or if you were given the same circuit only you would be missing the 1K resistor but you would have your voltmeter then you could say the voltage is 2.92V (4V - 1.08V on your meter) and since you know current is the same to find that resistor value you'd say 2.92V/2.92mA = 1K ohm resistor.