The emf induced across the wing-tips of a flying aircraft is of the order of several millivolts. Can this value be obtained using a sensitive millivoltmeter connected across the wing-tips? Explain your answer.
Not if connections are actually made to the wing tips. The wires to the terminals of the voltmeter will have the same emf induced, and this will cancel out the emf between the wing-tips.
I assume that the small emf is a result of the plane cutting across magnetic field lines of the earth.
If the wires leading to the ends of wing are NOT connected there I believe the EMF can be read. It will be induced in the lead wires of the voltmeter