Task (find): The article says a black room was set up for a system Tesla had previously shown throughout America. What kind of lighting system was shown there, and in the lecture image for that demonstration, what large dark shape stands behind him?

Condition: grounding
Answer: Alternating-current lighting; a tall rectangular backdrop or screen.
Answer correct: false
Evidence cited:
text: He attempted to develop a wireless lighting system based on near-field inductive and capacitive coupling and conducted a series of public demonstrations where he lit Geissler tubes and even incandescent light bulbs from across a stage.
prompt: Choose the evidence that helps answer the first part
granularity: sentence
text: Tesla demonstrating wireless lighting by "electrostatic induction" during an 1891 lecture at Columbia College via two long Geissler tubes (similar to neon tubes) in his hands
prompt: Choose the image that helps answer the question
granularity: image
Confidence: very
Helpfulness: very

Condition: nongrounding
Answer: Wireless lighting; a tall rectangular backdrop or screen.
Answer correct: true
Evidence cited:
text: A specially darkened room had been set up where Tesla showed his wireless lighting system, using a demonstration he had previously performed throughout America and Europe; these included using high-voltage, high-frequency alternating current to light wireless gas-discharge lamps.
prompt: Choose the evidence that helps answer the first part
granularity: sentence
text: Tesla demonstrating wireless lighting by "electrostatic induction" during an 1891 lecture at Columbia College via two long Geissler tubes (similar to neon tubes) in his hands
prompt: Choose the image that helps answer the question
granularity: image
Confidence: very
Helpfulness: very