Use a voltmeter.
tape measure?
It depends on what kind of reading you want. An electrician will usually carry around a multimeter which can measure voltage, current, and resistance. Another piece of equipment that can "determine the presence of electric charge" would be a Electromagnetic Field (EMF) detector, since all electrical appliances/wires produce an electromagnetic field. There could be others, but those are the two I'm aware of.
Because an angle is a degree. It would be pretty silly to measure them in, say, horsepower, no?
The same way you measure a TV screen, diagonally (any corner to opposite corner).
direction of flow
"voltmeter"
You can measure the emf of a cell by using a voltmeter, as this draws current from a cell. You can use the voltage, the emf, and the load resistance to determine the internal resistance of the cell.
To measure the total emf simply connect the battery and voltmeter with the right terminals , but to measure the terminal potential difference which is less than the emf the voltmeter is connected in parallel with the battery
Volts are the measure of Eletro motive force. (EMF)
EMF apps may not always accurately measure electromagnetic fields. Their effectiveness can vary depending on the app and the device it is used on. It is recommended to use professional equipment for precise measurements.
EMF, or electromotive force, is a measure of the energy provided by a source (such as a battery) to move a unit charge around a closed circuit. It is responsible for driving the flow of electric current in a circuit. EMF is measured in volts.
EMF stands for "electromotive force" and is (more or less) a synonym for voltage. Despite the name, it's not really a "force" in the physical sense (EMF is measured in, unsurprisingly, volts, while forces are measured in newtons), and is more properly referred to as a potential. See the related link for more details.
A voltmeter measures potential difference across a component, which may not necessarily be equal to the EMF of a cell due to internal resistance in the cell and voltage drops across other components in the circuit. To accurately measure the EMF of a cell, a potentiometer or a high-resistance voltmeter is used in conjunction with a null point method.
you can, but you will not get accurate answer as voltmeter consumes some current. so, potentiometer is used instead to measure emf ---- the potentiometer must be set to the expected emf from the cell before you put the zero detector in circuit if its set too high it will charge the cell too low it will load the cell perhaps if you dont know the voltage of the cell before you measure it you should get a hi impedance voltmeter(electrometer) to set the potentiometer as close as you can manage before you connect the zero detector
EMF (E''electromotive Force'') is another term for Volts, hence the E in electronic formulas and EMF is measured with a volt meter. A potentiometer is not a meter at all, it is a variable resistor
emf in volts
EMF (Volts) Resistance (Ohms), and most of the time, Current (Amperes, or more likely, mili Amperes)