How many 200 W/200 V incandescent lamps connected in series would consume the same total power as a single 100 W/200 V incandescent lamp?

An average-reading digital multimeter reads $$10V$$ when fed with a triangular wave, symmetric about the time axis. For the same input an rms reading meter will read.

The figure shows a three phase delta connected load supplied from a $$400V,$$ $$50Hz,$$ $$3\phi $$ balanced source. The pressure coil and current coil of a wattmeter are connected to the load as shown. With the coil polarities suitably selected to ensure a positive deflection. The wattmeter reading will be.

The two inputs of a $$CRO$$ are fed with two stationary periodic signals. In the $$X$$-$$Y$$ mode, the screen shows a figure which changes from ellipse to circle and back to ellipse with its major axis changing orientation slowly and repeatedly. The following inference can be made from this.