Switch-on behavior of a light bulb with Cobra SMARTsense

Principle

Incandescent lamps have a very low cold resistance compared to the resistance in running (warm) operation. This results in a current peak when the bulb is switched on, which is considerably higher than the rated current. Accordingly, it is often the case that incandescent bulbs burn out precisely during the switch-on process.

Benefits

• Particularly comprehensible and didactically prepared description of the experiment (reference to everyday life etc.) incl. protocol questions.
• Future-oriented teaching: Integration into digital science lessons with tablets or smartphones.
• Increased motivation among students through use of the intuitive measureAPP.
• Increased media literacy.
• No additional cable connections between the modules necessary - clearer and faster set-up.
• contact safety due to puzzle-like interlocking building blocks
• Hard gold-plated, corrosion-resistant contacts
• Double learning success: electrical circuit diagram visible on the upper side and real components on the lower side

Tasks

The incandescent lamp is connected in series with an ammeter and a switch. The course of the current when the switch is closed is measured, allowing conclusions to be drawn about the low cold resistance of the incandescent lamp.

Learning Objectives

By means of this experiment, the students should understand that the inrush current is much greater than the rated current due to the low cold resistance of the incandescent lamp. They should understand that this is why light bulbs almost always burn out when they are switched on.