A precise measurement guarantees accuracy of the measured quantity.

A $$0$$-$$10$$ $$mA$$ $$PMMC$$ ammeter reads $$4$$ $$mA$$ in a circuit. Its bottom control spring snaps suddenly. The meter will now read nearly

A d.c. potentiometer is designed to measure up to about $$2$$ $$V$$ with a slide wire of $$800$$ mm. A standard cell of emf $$1.18V$$ obtains balance at $$600$$ mm. A test cell is seen to obtain balance at $$680$$ mm. The emf of the test cell is

A lissajous pattern, as shown in figure below, is observed on the screen of a $$CRO$$ when voltages of frequencies $${f_x}$$ and $${f_y}$$ are applied to the $$x$$ and $$y$$ plates respectively. $${f_x}:{f_y}$$ is then equal to