School chart with a thin cord at the top to hang it up. The school chart ...

An ammeter or current meter is a measuring instrument that measures the magnitude of electric current. ...

An ammeter or current meter is a measuring instrument that measures the magnitude of electric current. ...

School chart with a wooden stick at the top and bottom. The top stick has a ...

A man is led away by six soldiers.

The school chart shows a barricade with dozens of people including one waving a flag. In ...

School chart with holes at the top to hang it up. A black and white drawing ...

An ammeter or current meter is a measuring instrument that measures the magnitude of electric current. ...

A wattmeter is an analogue electrical measuring instrument used to calculate electrical power. This wattmeter was ...

A wattmeter is an analogue electrical measuring instrument used to calculate electrical power. This wattmeter was ...

A wattmeter is an analogue electrical measuring instrument used to calculate electrical power. This wattmeter was ...

An oscilloscope is an electronic measuring instrument that can effectively visualise cyclic variations in an electrical ...

Rubens is in the centre in front of a canvas. Next to him are two children. ...

This analogue moving coil device was used in an electronic clock. The time corresponded to an ...

A wooden viewing box has an opening at the front and top. Inside is an oblique ...

An ammeter or current meter is a measuring instrument that measures the magnitude of electric current. ...

An ammeter or current meter is a measuring instrument that measures the magnitude of electric current. ...

An ammeter or current meter is a measuring instrument that measures the magnitude of electric current. ...

A voltmeter is a device used to measure electrical voltage. The value is indicated in volts. ...

Hydrostatic Mohr and Westphal balance. The Mohr balance determines the specific gravity of liquids.

Roll-up school chart with a wooden stick at the top and bottom. The top stick has ...

School chart with a thin cord at the top to hang it up. The school chart ...