a) If resistors are connected in series which physical quantity will remain the same in all the resistors?

                                                                                                                        or

b) Should a voltmeter have a low or high resistance?

a) Resistors are said to be connected in a series pattern if the same amount of current flows through them. Therefore, the result is also true, i.e., if they are connected in series, then the same amount of current flows through them.

Series connection of resistors

If the resistors in a circuit are all connected in series, like the figure given above, then the total resistance of the system is given by the following relation. 

𝑅_{𝑡𝑜𝑡𝑎𝑙} = 𝑅₁ + 𝑅₂ ........... + 𝑅_𝑛 

The total resistance of the system is just the total of individual resistances. 

For example, consider the following sample problem. 

A resistor with an electrical resistance value of 100 𝑜ℎ𝑚𝑠 is connected to another with a resistance value of 200 𝑜ℎ𝑚𝑠. The two resistances are connected in series. What is the total resistance across the system?

Here, 

𝑅₁ = 100 Ω and 𝑅₂ = 200 Ω 

𝑅_{𝑡𝑜𝑡𝑎𝑙} = 𝑅₁ + 𝑅₂ = 100 Ω + 200 Ω = 300 Ω.

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b) A voltmeter is a device used to measure the electrical potential difference between two points of an electrical circuit. Analog voltmeters shift the pointer around a range following the circuit's voltage; digital voltmeters show the voltage using an analog-to-digital converter. A voltmeter measures the voltage difference between the two points (say, on opposite sides of a resistor), but it does not adjust the amount of current passing between these two points through the device. Therefore has very high resistance so that it does not draw current. The lower the resistance the voltmeter puts across the load, the more wrong the reading will be on the voltmeter. The best voltmeter will have such a high resistance that it will not significantly change the current in the circuit. Good, modern voltmeters have several megohm input resistance. Ideally, an ammeter should have zero resistance and an infinite voltmeter resistance to give correct readings.