BRAIN TEASERS

enter your answer and press button OK

Find the pattern to determin...

Find the pattern to determine what the missing number is.

Correct answers: 98

The first user who solved this task is Roxana zavari.

#brainteasers #math

Register with your Google Account and start collecting points.

Check your ranking on list.

When I was married, my wife us...

When I was married, my wife used to call me handsome. As a matter of fact, we are now divorced but she STILL calls me handsome.

Every time I have some money, she says, HANDSOME OVER.

Jokes of the day - Daily updated jokes. New jokes every day.

Follow Brain Teasers on social networks

Brain Teasers

puzzles, riddles, mathematical problems, mastermind, cinemania...

Crystal rectifier

In 1874, a paper by Ferdinand Braun (1850-1918) was published in the Annalen der Physik und Chemie describing his discovery of the electrical rectifier effect. He observed that certain crystals of metal sulphides have a larger or smaller resistance to an electric current, depending on its direction of flow. He used a galena crystal, a semiconductor material composed of lead sulfide. He found the rectifying effect especially true if at least one of the electrodes was a pointed wire. Thus, he had discovered the point-contact rectifier effect, the first semiconductor device. This effect wasn't used until over 30 years later in the form of the “cat's whisker”crystal radio detector which ultimately led to the point-contact transistor first produced in 1948.

This site uses cookies to store information on your computer. Some are essential to help the site properly. Others give us insight into how the site is used and help us to optimize the user experience. See our privacy policy.